NUVEEN UNIT TRUSTS SERIES 91
487, 2000-05-15
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<PAGE>


                                                1933 Act File No. 333-36520
                                                1940 Act File No. 811-08103


                      Securities and Exchange Commission
                            Washington, D.C. 20549
                                 Amendment No. 2
                                      To
                                   Form S-6

For Registration under the Securities Act of 1933 of Securities of Unit
Investment Trusts Registered on Form N-8B-2

A.  Exact name of Trust:  Nuveen Unit Trusts, Series 91

B.  Name of Depositor:    John Nuveen & Co. Incorporated

C.  Complete address of Depositor's principal executive offices:

                              333 West Wacker Drive
                              Chicago, Illinois  60606

D.  Name and complete address of agents for service:

                              John Nuveen & Co. Incorporated
                              Attention:  Alan G. Berkshire
                              333 West Wacker Drive
                              Chicago, Illinois  60606

                              Chapman and Cutler
                              Attention:  Eric F. Fess
                              111 West Monroe Street
                              Chicago, Illinois  60603

It is proposed that this filing will become effective (check appropriate box)

- ----
:  :  immediately upon filing pursuant to paragraph (b)
- ----
:  :  on (date) pursuant to paragraph (b)
- ----
:  :  60 days after filing pursuant to paragraph (a)
- ----
:  :  on (date) pursuant to paragraph (a) of rule 485 or 486
- ----

E.    Title of securities being registered:  Units of fractional undivided
      beneficial interest.

F.    Approximate date of proposed sale to the public: As soon as practicable
      after the effective date of the Registration Statement.

- ----
:X :  Check box if it is proposed that this filing will become effective on
- ----  May 15, 2000 at 1:30 P.M. pursuant to Rule 487.


<PAGE>



                                 [NUVEEN LOGO]

Nuveen Unit Trusts, Series 91

Nuveen--Standard & Poor's Quality Buyback Portfolio, May 2000

         Prospectus Part A dated May 15, 2000

 .Seeks Capital Appreciation

 .A Time-Tested Investment Strategy

 .Interests in Companies Engaged in Stock Buyback Programs
 .Rollover Option
 .Letter of Intent Available



The Securities and Exchange Commission has not approved or disapproved these
securities or passed upon the adequacy of this prospectus. Any representation
to the contrary is a criminal offense.

EQU-05-00-P
<PAGE>


Nuveen Unit Trusts, Series 91             CUSIP Nos:
Nuveen--Standard & Poor's Quality         Dividend in  Reinvested  Wrap
Buyback Portfolio, May 2000               Cash
                                          67066W489    67066W497   67066W505

Overview

Nuveen Unit Trusts, Series 91 in-
cludes the unit investment trust
listed above. The Nuveen--Standard
and Poor's Quality Buyback Portfolio
(the "Portfolio") seeks to provide
above-average capital appreciation by
investing in common stocks of compa-
nies with strong historical earnings
and dividends and credit quality. The
Portfolio will be offered for sale in
the primary market through July 14,
2000. The Portfolio is scheduled to
terminate in approximately 14 months.

 Contents

 2Overview

 3 Nuveen--Standard & Poor's Quality
   Buyback Portfolio, May 2000
 3 Risk/Return Summary
 3 Investment Objective
 3 Investment Strategy
 3 Security Selection
 4 Industry Diversification
 4 Primary Risks
 4 Investor Suitability
 4 Fees and Expenses
 6 Quality Buyback Strategy
   Historical Performance
 7 Schedule of Investments
 8 How to Buy and Sell Units
 8 Investing in the Portfolio
 8 Sales or Redemptions
 9 Risk Factors
 9 Distributions
 9 Income Distributions
 9 Capital Distributions
 9 General Information
 9 Termination
 9 The Sponsor
 9 Standard & Poor's
10 Dealer Concessions
10 Optional Features
10 Rollover Trusts
10 Letter of Intent
10 Reinvestment
10 Nuveen Mutual Funds
11 Statement of Condition
12 Report of Independent Public
   Accountants

 For the Table of Contents of Part
 B, see Part B of the Prospectus.
- ---------




 Units are not deposits or obligations of, or guaranteed by any bank. Units are
 not FDIC insured and involve investment risk, including the possible loss of
 principal.

"Standard & Poor's" and "S&P" are trademarks of the McGraw-Hill Companies, Inc.
and have been licensed for use by John Nuveen & Co. Incorporated ("Nuveen" or
the "Sponsor"). The Portfolio is not sponsored, managed, sold or promoted by
Standard & Poor's.

                                      ---
                                       2
<PAGE>


Nuveen--Standard & Poor's Quality Buyback Portfolio, May 2000

Risk/Return Summary

Investment Objective

The Portfolio seeks to provide above-average capital appreciation with a mod-
erated level of risk as compared to the S&P 500.

Investment Strategy

The Portfolio consists of the stocks of the companies selected by Nuveen using
a screening model developed with the assistance and expertise of Standard &
Poor's. The stocks are expected to remain in the Portfolio until termination.
The Sponsor intends to create future portfolios that follow the same invest-
ment strategy. One such portfolio is expected to be available when the Portfo-
lio terminates. If these future portfolios are available, you may reinvest
into one of the portfolios at a reduced sales charge. Each portfolio is de-
signed to be part of a longer-term strategy, and the Sponsor believes that
more consistent results are likely if the strategy is followed for at least
three to five years.

Security Selection

 . We select the stocks in the Portfolio by applying on April 28, 2000, a four-
  step screening model (the "Quality Buyback Strategy"). The Quality Buyback
  Strategy only selects the stocks of companies that satisfy all of the fol-
  lowing conditions:

 Market Capitalization--Companies with market capitalizations equal to or in
 excess of $500 million.

 Credit Ratings--Companies that have a Standard & Poor's Issuer Credit Rating
 of at least AA-. A Standard & Poor's issuer credit rating is its opinion of
 the issuer's creditworthiness concerning a specific senior financial obliga-
 tion or program. Standard & Poor's determines its credit ratings based on
 likelihood of payment, nature and provisions of the obligation, and protec-
 tion against bankruptcy and other laws. The AA- symbol means the obligor has
 a very strong capacity to meet its financial commitment.

 Stock Rankings--Companies that are ranked A+ or A by Standard & Poor's Earn-
 ings and Dividend Rankings for Common Stocks, its highest rankings. Standard
 & Poor's determines its stock rankings primarily on the growth and stability
 of per-share earnings and dividends. It assigns a symbol to each stock, which
 ranges from A+ for the highest ranked stocks to D for those stocks Standard &
 Poor's considers to be the most speculative. These rankings are not intended
 to predict stock price movements.

 Share Reduction--Companies that have reduced the number of common shares out-
 standing (as adjusted), generally through stock buybacks, by at least 1% over
 the last year (as of a company's most recent fiscal quarter for which infor-
 mation is available) and paid cash dividends during the most recent one-year
 period. Shares are adjusted in response to stock splits, stock dividends and
 other corporate actions to minimize potential distortions.

 . Standard & Poor's believes that:

 --Share reduction is typically the result of a share buyback program executed
  by the company and generally reflects a strong cash flow position, and in
  turn, high quality earnings.

 --A buyback program may provide an indirect measure of the value of the
  stock, in that management has judged that an investment in the company's own
  stock offers more attractive returns than those available from other invest-
  ment sources.

 --Share reduction is typically associated with companies that are more likely
  to be characterized as "stable" rather than "aggressive growth." Companies
  seeking very rapid (and potentially volatile) growth are unlikely to divert
  resources to share reduction activities.

                                      ---
                                       3
<PAGE>

Industry Diversification

Based upon the principal business of each issuer and current market values,
the Portfolio represents the following industries:

<TABLE>
<CAPTION>
                           Approximate
Industry               Portfolio Percentage
- --------               --------------------
<S>                    <C>
Capital Equipment             10.02%
Electrical Integrated         10.03%
Financial Services            10.02%
Health Care                    9.97%
Household Products            20.03%
Insurance                      9.95%
Manufacturing                 10.04%
Media                         10.01%
Technology                     9.93%
                             -------
    Total                    100.00%
                             =======
</TABLE>

Primary Risks

You can lose money by investing in the Portfolio. In addition, the Portfolio
may not perform as well as you hope. These things can happen for various rea-
sons, including:

 . Stock prices can be volatile.

 . Share prices or dividend rates on the stocks may decline during the life of
  the Portfolio.

 . The Portfolio is not actively managed and may continue to purchase or hold a
  stock included in the Portfolio even though the stock's outlook or its mar-
  ket value or yield may have changed.

Investor Suitability

The Portfolio may be suitable for you if:

 . You are seeking the opportunity to purchase a defined portfolio of stocks
  that are selected through the application of the Quality Buyback Strategy;

 . You want capital appreciation potential;

 . The Portfolio is part of a longer term investment strategy that includes the
  investment in subsequent portfolios, if available; and

 . The Portfolio represents only a portion of your overall investment portfolio.

The Portfolio is not appropriate for you if:

 . You are unwilling to take the risks involved with owning an equity invest-
  ment;

 . You are seeking preservation of capital or high current income; or

 . You do not have a long-term investment horizon.

Fees and Expenses

This table shows the fees and expenses you may pay, directly or indirectly,
when you invest in the Portfolio.

Shareholder Fees

<TABLE>
<CAPTION>
                                                     Amount per Unit Amount per
                                                      (based on $10    $1,000
                                                          Unit)      Invested(1)
                                                     --------------- -----------
<S>                                                  <C>             <C>
Sales Charge
Upfront Sales Charge(2).............................      1.00%        $10.00
Deferred Sales Charge(3)............................      1.95%        $19.50
                                                        --------       ------
Total Maximum Sales Charges.........................      2.95%        $29.50


Estimated Annual Operating Expenses

<CAPTION>
                                                                     Approximate
                                                     Amount per Unit % of Public
                                                      (based on $10   Offering
                                                          Unit)       Price(1)
                                                     --------------- -----------
<S>                                                  <C>             <C>
Trustee's Fee.......................................    $0.00950       0.0950%
Sponsor's Supervisory Fee...........................    $0.00350       0.0350%
Bookkeeping and Administrative Fee..................    $0.00250       0.0250%
Creation and Development Fee(4).....................    $0.02500       0.2500%
Other Operating Expenses(5).........................    $0.01175       0.1175%
                                                        --------       ------
Total...............................................    $0.05225       0.5225%
Maximum Organization Costs(6).......................    $  0.022         0.22%
</TABLE>
- ---------
(1) Based on 100 Units with a $10 per Unit Public Offering Price as of the
    Initial Date of Deposit.

(2) As provided below, the Upfront Sales Charge equals the difference between
    the Maximum Sales Charge of 2.95% and any remaining deferred sales
    charges. Accordingly, the percentage amount of the Upfront Sales Charge
    will vary over time.

(3) The Deferred Sales Charge is a fixed dollar amount of $0.195 per Unit. The
    percentage provided is based on a $10 Unit as of the Initial Date of De-
    posit and will vary over time.

(4) The Creation and Development Fee compensates the Sponsor for creating and
    developing the Portfolio. The Portfolio accrues the fee daily during the
    life of the Portfolio based on its average net asset value and

                                      ---
                                       4
<PAGE>

   pays the Sponsor monthly. In connection with the Creation and Development
   Fee, in no event will the Sponsor collect over the life of the Portfolio
   more than 0.75% of a Unitholder's initial investment. The per Unit Creation
   and Development Fee provided above is based on a $10 per Unit Public Offer-
   ing Price on the Initial Date of Deposit. The actual annual Creation and
   Development Fee that will be charged is 0.25% of average daily net assets
   and will exceed the per Unit fee provided above for Units whose value ex-
   ceeds $10 per Unit.

(5) Other Operating Expenses include annual licensing fees paid to cover a li-
    cense to use service marks, trademarks, trade names, databases and re-
    search of Standard & Poor's but do not include brokerage costs and other
    transactional fees.

(6) Organization costs are deducted from Portfolio assets at the earlier of
    the close of the initial offering period or 6 months after Initial Date of
    Deposit.

You will pay both an Upfront and a Deferred Sales Charge. The Upfront Sales
Charge equals the difference between the Total Maximum Sales charge of 2.95%
of the Public Offering Price and any remaining deferred sales charges. The De-
ferred Sales Charges are $0.195 per Unit and are deducted monthly in install-
ments of $0.0195 per Unit on the last business day of each month from July 31,
2000 through April 30, 2001.

The maximum per Unit sales charges are reduced as follows:

<TABLE>
<CAPTION>
                                                                          Total
                                                     Upfront  Deferred   Maximum
                                                      Sales    Sales      Sales
                 Number of Units(1)                 Charge(2)  Charge    Charge
 -------------------------------------------------  --------- --------   -------
 <S>                                                <C>       <C>        <C>
 Less than 5,000..................................    1.00%    $0.195     2.95%
 5,000 to 9,999...................................    0.75%    $0.195     2.70%
 10,000 to 24,999.................................    0.50%    $0.195     2.45%
 25,000 to 49,999.................................    0.25%    $0.195     2.20%
 50,000 to 99,999.................................    0.00%    $0.195     1.95%
 100,000 or more..................................    0.00%    $0.195(3)  1.20%
</TABLE>
- ---------
(1) Sales charge reductions are computed both on a dollar basis and on the ba-
    sis of the number of Units purchased, using the equivalent of 5,000 Units
    to $50,000, 10,000 Units to $100,000 etc., and will be applied on that ba-
    sis which is more favorable to you.
(2) The Upfront Sales Charge is based on the Unit price on the Initial Date of
    Deposit. The percentage amount of the Upfront Sales Charge will vary as
    the Unit price varies and after deferred charges begin.
(3) All Units are subject to the same Deferred Sales Charges. When the de-
    ferred charges exceed the Maximum Sales Charge, you will be given extra
    Units at the time of purchase.

As described in "Public Offering Price" in Part B of the Prospectus, certain
classes of investors are also entitled to reduced sales charges. The secondary
market sales charges for the Portfolio are the same as the primary market
charges provided above.

Example

This example may help you compare the cost of investing in the Portfolio to
the cost of investing in other funds.

The example assumes that you invest $10,000 in the Portfolio for the periods
indicated and then either redeem or do not redeem your Units at the end of
those periods. The example also assumes a 5% return on your investment each
year and that the Portfolio's operating expenses stay the same. The example
does not include brokerage costs and other transactional fees. Although your
actual costs may be higher or lower, based on these assumptions your costs
would be:

<TABLE>
<CAPTION>
 1 Year                3 Years                            5 Years                            10 Years
 -------               -------                           ---------                           ---------
 <S>                   <C>                               <C>                                 <C>
 $368.51               $924.09                           $1,505.39                           $3,079.07
</TABLE>

While the Portfolio has a term of approximately 14 months, you may be able to
invest in future portfolios with reduced sales charges. These future sales
charges are included in the amounts provided above.

See "Trust Operating Expenses" in Part B of the Prospectus for additional in-
formation regarding expenses.


                                      ---
                                       5
<PAGE>

Quality Buyback Strategy Historical Performance

The Sponsor intends to create future portfolios that follow the Quality
Buyback Strategy. A portfolio is expected to be available upon the Portfolio's
termination. To give you some indication of the performance potential of the
Quality Buyback Strategy, the following table compares the constructed perfor-
mance of the Quality Buyback Strategy stocks (but not any actual portfolio)
with the actual performance of two general market indices.

The constructed returns of the Quality Buyback Strategy reflect the applica-
tion of the strategy once every year and include the actual sales charges and
estimated expenses of the Portfolio. The performance provided is no assurance
of future results of either the Quality Buyback Strategy or any portfolio.

                        COMPARISON OF TOTAL RETURNS(1)

<TABLE>
<CAPTION>
                                                        Quality
                                                        Buyback
                                                        Strategy S&P 500  DJIA
                                                         Total    Total   Total
                                                        Returns  Returns Returns
                                                          (2)      (3)     (3)
Year                                                    -------- ------- -------
<S>                                                     <C>      <C>     <C>
1982...................................................  19.8%    20.4%   27.2%
1983...................................................  36.1%    22.3%   26.1%
1984...................................................  17.7%     6.0%    1.4%
1985...................................................  32.0%    31.1%   33.6%
1986...................................................  29.6%    18.5%   27.3%
1987...................................................   9.1%     5.7%    5.6%
1988...................................................  22.9%    16.3%   16.3%
1989...................................................  29.7%    31.2%   32.2%
1990...................................................   6.0%    -3.1%   -0.5%
1991...................................................  25.5%    30.0%   24.3%
1992...................................................   9.2%     7.4%    7.4%
1993...................................................  -4.1%     9.9%   17.0%
1994...................................................   8.8%     1.3%    5.0%
1995...................................................  33.1%    37.1%   36.9%
1996...................................................  18.5%    22.7%   28.9%
1997...................................................  40.0%    33.1%   24.9%
1998...................................................  18.2%    28.1%   18.2%
1999...................................................   3.7%    21.0%   27.2%
2000 through 4/28......................................  -2.0%    -0.7%   -6.2%
</TABLE>

(1) To compute Total Returns, we add changes in market value and dividends
    that would have been received during the year, and divide the sum by the
    opening market value for the year. Return from a Portfolio will differ
    from constructed Quality Buyback Strategy returns for several reasons in-
    cluding the following:

  . the Portfolio bears brokerage commissions in buying and selling stocks;
    Quality Buyback Strategy returns do not reflect any commissions;

  . Quality Buyback Strategy returns are for calendar years, while the Portfo-
    lio begins and ends on a specific date;

  . Units are bought and sold based on the closing stock prices on the ex-
    change, while the Portfolio may buy and sell stocks at prices during the
    trading day;

  . the Portfolio may not be fully invested at all times; and

  . stocks in the Portfolio may not be weighted equally at all times;

(2) The Quality Buyback Strategy common stocks were selected by applying the
    Quality Buyback Strategy as of the business day prior to the beginning of
    each year commencing on December 31, 1981. The constructed strategy re-
    turns would be different if the portfolios were determined in years other
    than those selected.

(3) The S&P 500 returns assume dividends are reinvested upon receipt. The DJIA
    returns assume that dividends are reinvested each month. Although the
    Portfolio seeks to outperform the S&P 500 and DJIA, there is no guarantee
    that it will.

                                      ---
                                       6
<PAGE>

- -------------------------------------------------------------------------------
Schedule of Investments

(at the Initial Date of Deposit, May 15, 2000)

      Nuveen--Standard & Poor's Quality Buyback Portfolio, May 2000

<TABLE>
<CAPTION>
                                                                   Percentage
                                                                  of Aggregate   Market       Cost of     Current
Number of       Name of Issuer of Securities        Stock  Credit   Offering     Value      Securities    Dividend
 Shares              (Ticker Symbol)(1)            Ranking Rating    Price     per Share  to Portfolio(2) Yield(3)
- ------------------------------------------------------------------------------------------------------------------
<S>        <C>                                     <C>     <C>    <C>          <C>        <C>             <C>
    381    Cincinnati Financial Corporation (CINF)   A      AA-      10.02%    $ 39.37500    $ 15,002      1.93%
    242    Gannett Co., Inc. (GCI)                   A      AA-      10.01%      61.93750      14,989      1.36%
    402    The Gillette Company (G)                  A      AA       10.02%      37.31250      15,000      1.74%
    113    Hewlett-Packard Company (HWP)             A+     AA-       9.93%     131.56250      14,867      0.49%
    236    Jefferson-Pilot Corporation (JP)          A+     AA        9.95%      63.12500      14,898      2.34%
    218    Merck & Co., Inc. (MRK)                   A+     AAA       9.97%      68.43750      14,919      1.69%
    177    Minnesota Mining and Manufacturing
           Company (MMM)                             A      AA       10.04%      84.93750      15,034      2.73%
    376    Pitney Bowes Inc. (PBI)                   A+     AA       10.02%      39.87500      14,993      2.86%
    234    The Proctor & Gamble Company (PG)         A      AA       10.01%      64.06250      14,991      2.00%
    696    TECO Energy, Inc. (TE)                    A      AA-      10.03%      21.56250      15,008      6.21%
  -----                                                              ------                  --------
  3,075                                                                100%                  $149,701
  =====                                                              ======                  ========
</TABLE>
- ---------

(1) All Securities are represented by contracts to purchase such Securities
    for the performance of which an irrevocable letter of credit has been de-
    posited with the Trustee. The contracts to purchase the Securities were
    entered into by the Sponsor on May 12, 2000.

(2) The cost of the Securities to the Portfolio represents the aggregate un-
    derlying value with respect to the Securities acquired (generally deter-
    mined by the closing sale prices of the listed securities on the business
    day preceding the Initial Date of Deposit). The valuation of the Securi-
    ties has been determined by the Trustee. As of the Initial Date of Depos-
    it, other information regarding the Securities is as follows:

<TABLE>
<CAPTION>
     <S>                                                              <C>
     Value of Securities............................................. $149,701
     Cost to Sponsor................................................. $150,094
     Gain (loss)..................................................... $   (393)
     Estimated Annual Income Distributions per Portfolio............. $0.23147
     Estimated Net Annual Income Distributions per Unit.............. $0.17922
</TABLE>

  Estimated Annual Income Distributions are based on the most recent ordinary
  dividend paid on that Security. Estimated Net Annual Income Distributions
  per Unit are based on the number of Units and the aggregate value of the
  Securities per Unit as of the Initial Date of Deposit. Investors should
  note that the actual amount of income distributed per Unit by the Portfolio
  will vary from the estimated amount due to a variety of factors including,
  changes in the items described in the preceding sentence, expenses and
  actual dividends declared and paid by the issuers of the Securities.

(3) Current Dividend Yield for each Security was calculated by annualizing the
    last quarterly or semi-annual ordinary dividend declared on that Security
    and dividing the result by that Security's closing sale price on the busi-
    ness day prior to the Initial Date of Deposit.

Advertising and sales literature may include brief descriptions of the princi-
pal businesses of the companies included in the Portfolio.

Please note that if this Prospectus is used as a preliminary prospectus for
future Nuveen Defined Portfolios, the portfolio will contain different stocks
from those described above.

- -------------------------------------------------------------------------------

                                      ---
                                       7
<PAGE>

How to Buy and Sell Units

Investing in the Portfolio

The minimum investment is normally $1,000 or 100 Units, whichever is less.
However, for IRA purchases the minimum investment is $500 or the nearest whole
number of Units whose value is less than $500.

You can buy Units from any participating dealer.

As of May 15, 2000, the Initial Date of Deposit, the per Unit Public Offering
Price for the Portfolio is $10.00. As described above, Units are subject to an
upfront sales charge that is equal to the difference between the Total Maximum
Sales Charge of 2.95% of the Public Offering Price and the remaining deferred
sales charges. If the Portfolio has any remaining deferred sales charges, you
will also pay those charges. The Public Offering Price includes the Upfront
Sales Charge and the estimated organization cost of $.022 per Unit. The Public
Offering Price changes every day with changes in the price of the securities.
As of the close of business on May 15, 2000, the number of Units of the Port-
folio may be adjusted so that the per Unit Public Offering Price will equal
$10.00.

If you are buying Units with assets received from the redemption or termina-
tion of another Nuveen Defined Portfolio, you will pay a reduced sales charge
of $0.195 per Unit. You may also buy Units with that sales charge if you are
purchasing Units with the termination proceeds from a non-Nuveen unit trust
with a similar investment strategy. Such purchases entitled to this sales
charge reduction may be classified as "Rollover Purchases."

Wrap Account Purchases and certain other investors described in Part B of the
Prospectus, may buy Units with a sales charge equal to the portion of the
sales charge retained by the Sponsor for non-breakpoint purchases (approxi-
mately 0.70% of the Public Offering Price). Wrap account arrangements gener-
ally involve additional fees charged by your broker, financial advisor or fi-
nancial planner.

The discount for Wrap Account Purchases is available whether or not you pur-
chase Units with the Wrap CUSIP option. However, if you purchase Units with
the Wrap CUSIP option you should be aware that all distributions (other than
the liquidation distribution) from such Units will be invested in additional
Units of the Portfolio.

The Portfolio's securities are valued by the Evaluator, The Chase Manhattan
Bank, generally on the basis of their closing sales prices on the applicable
national securities exchange or The Nasdaq Stock Market, Inc. every business
day.

The Sponsor intends to periodically create additional Units of the Portfolio.
See "Nuveen Defined Portfolios" and "Composition of Trusts" in Part B of the
Prospectus for more details.

See "Public Offering Price" and "Market for Units" in Part B for additional
information.

Sales or Redemptions

Units may be redeemed by the Trustee, The Chase Manhattan Bank, on any busi-
ness day at their current market value. Unitholders who purchase at least
1,000 Units or whose Units are worth $10,000 may elect to be distributed the
underlying stock, rather than cash, if the election is made at least five
business days prior to the Portfolio's termination.

Although not obligated to do so, the Sponsor, John Nuveen & Co. Incorporated,
may maintain a market for Units and offer to repurchase the Units at prices
based on their current market value. If a secondary market is not maintained,
a Unitholder may still redeem Units through the Trustee.

During the period ending with the earlier of six months after the Initial Date
of Deposit or the end of the initial offering period, the price at which the
Trustee will redeem Units and the price at which the Sponsor may repurchase
Units include estimated organization costs. After such period, the amount paid
will not include such estimated organization costs.

Any applicable deferred sales charges remaining on Units at the time of their
sale or redemption will be collected at that time.

See "Redemption" and "Market for Units" in Part B of the Prospectus for de-
tails.


                                      ---
                                       8
<PAGE>

Risk Factors

You can lose money by investing in the Portfolio. Recently, equity markets
have experienced significant volatility. Your investment is at risk primarily
because of:

 . Market risk

  Market risk is the risk that a particular stock in the Portfolio, the Port-
  folio itself or stocks in general may fall in value. Market value may be af-
  fected by a variety of factors including:

  --General stock market movements;

  --Changes in the financial condition of an issuer or an industry;

  --Changes in perceptions about an issuer or an industry;

  --Interest rates and inflation;

  --Governmental policies and litigation; and

  --Purchases and sales of securities by the Portfolio.

 . Inflation risk

  Inflation risk is the risk that the value of assets or income from invest-
  ments will be less in the future as inflation decreases the value of money.

Distributions

Income Distributions

Cash dividends received by the Portfolio, net of expenses, will be paid each
June 30 and December 31 ("Income Distribution Dates"), beginning June 30,
2000, to Unitholders of record each June 15 and December 15 ("Income Record
Dates"), respectively.

Capital Distributions

Distributions of funds in the Capital Account, net of expenses, will be made
when the Portfolio terminates. In certain circumstances, additional distribu-
tions may be made.

See "Distributions To Unitholders" in Part B of the Prospectus for more de-
tails.

General Information

Termination

Commencing on July 13, 2001, the Mandatory Termination Date, the securities in
the Portfolio will begin to be sold as prescribed by the Sponsor. The Trustee
will provide written notice of the termination to Unitholders which will spec-
ify when certificates may be surrendered.

Unitholders will receive a cash distribution within a reasonable time after
the Portfolio terminates. However, Unitholders who purchase at least 1,000
Units or whose Units are worth $10,000 may elect to be distributed the under-
lying stock if the election is made at least five business days prior to the
Portfolio's termination. See "Distributions to Unitholders" and "Other Infor-
mation--Termination of Indenture" in Part B of the Prospectus for more de-
tails.

The Sponsor

Since our founding in 1898, John Nuveen & Co. Incorporated has been synonymous
with investments that withstand the test of time. Today, we offer a range of
equity and fixed-income unit trusts designed to suit the unique circumstances
and financial planning needs of our investors. Nuveen, a leader in tax-effi-
cient investing, believes that a carefully selected portfolio can play an im-
portant role in building and sustaining the wealth of a lifetime. Nuveen began
offering defined portfolios in 1961 and more than 1.5 million investors have
trusted Nuveen to help them maintain the lifestyle they currently enjoy.

The Prospectus describes in detail the investment objectives, policies and
risks of each Portfolio. We invite you to discuss the contents with your fi-
nancial advisor, or you may call us at 800-257-8787 for additional informa-
tion.

Standard & Poor's

Standard & Poor's has over 130 years experience providing investment informa-
tion and analysis to the financial community. Standard & Poor's offers more
than 60 research, analytical and financial information products and employs
over 50 experienced equity analysts.


                                      ---
                                       9
<PAGE>

Dealer Concessions

The Sponsor plans to allow a concession of 2.25% of the Public Offering Price
for primary and secondary market non-breakpoint purchases of Units to dealer
firms in connection with the sale of Units in a given transaction.

The concession paid to dealers is reduced or eliminated in connection with
Units sold in transactions to investors that receive reduced sales charges
based on the number of Units sold or in connection with Units sold in Rollover
Purchases, Wrap Account Purchases and to other investors entitled to the sales
charge reduction applicable for Wrap Account Purchases, as follows:

- -------------------------------------------------------------------------------

<TABLE>
<CAPTION>
                                                                          %
                                                                      Concession
Number of Units*                                                       per Unit
- ----------------                                                      ----------
<S>                                                                   <C>
Less than 5,000......................................................    2.25%
5,000 to 9,999.......................................................    2.00%
10,000 to 24,999.....................................................    1.75%
25,000 to 49,999.....................................................    1.50%
50,000 to 99,999.....................................................    1.25%
100,000 or more......................................................    0.60%
Rollover Purchases ..................................................   $0.13
Wrap Account
 Purchases...........................................................    0.00%
</TABLE>
* Sales charge reductions are computed both on a dollar basis and on the basis
of the number of Units purchased, using the equivalent of 5,000 Units to
$50,000, 10,000 Units to $100,000 etc., and will be applied on that basis
which is more favorable to you and may result in a reduction in the discount
per Unit.

See "Distributions of Units to the Public" in Part B of the Prospectus for ad-
ditional information on dealer concessions and volume incentives.

Optional Features

Rollover Trusts

The Sponsor intends to create other portfolios that follow the same investment
strategy. If these portfolios are available, you may be able to invest in such
similar portfolios with a reduced sales charge. These portfolios are expected
to be available upon the Portfolio's termination.

To elect to have your redemption proceeds invested into the applicable new
portfolio, if available, you must notify the Trustee of this election by the
Rollover Notification Date, July 6, 2001. Units of Rollover Unitholders will
be redeemed during the Special Redemption and Liquidation Period, July 2, 2001
through July 13, 2001, and invested in the portfolio then available.

See "Special Redemption, Liquidation and Investment in a New Trust" in Part B
of the Prospectus for details.

Letter of Intent (LOI)

Investors may use a Letter of Intent to get reduced sales charges on purchases
made over a 13-month period (and to take advantage of dollar cost averaging).
Unitholders will not be permitted to apply future rollover purchases to sat-
isfy the LOI amount. The minimum LOI investment is $50,000. See "Public Offer-
ing Price" in Part B of the Prospectus for details.

Reinvestment

Distributions from the Portfolio can be invested with no sales charge into
Nuveen mutual or money market funds. Also, income and certain capital distri-
butions from the Portfolio can be reinvested into additional Units of the
Portfolio without a sales charge. See "Distributions to Unitholders" and "Ac-
cumulation Plan" in Part B of the Prospectus for details.

Nuveen Mutual Funds

Portfolio purchases may be applied toward breakpoint pricing discounts for
Nuveen Mutual Funds. For more information about Nuveen investment products,
obtain a prospectus from your financial advisor.

                                      ---
                                      10
<PAGE>

Statement of Condition

(at the Initial Date of Deposit, May 15, 2000)

<TABLE>
<CAPTION>
                                                                        Quality
                                                                        Buyback
                                                                       Portfolio
                                                                       ---------
<S>                                                                    <C>
Trust Property
Investment in securities represented by purchase contracts(1)(2).....  $149,701
                                                                       ========
Liabilities and Interest of Unitholders
Liabilities:
  Deferred sales charge(3)...........................................  $  2,949
  Reimbursement of Sponsor for organization costs(4).................  $    333
                                                                       --------
     Total...........................................................  $  3,282
                                                                       ========
Interest of Unitholders:
  Units of fractional undivided interest outstanding.................    15,121
  Cost to investors(5)...............................................  $151,168
   Less: Gross underwriting commission(6)............................  $  4,416
   Less: Organization costs(4).......................................  $    333
                                                                       --------
  Net amount applicable to investors.................................  $146,419
                                                                       --------
     Total...........................................................  $149,701
                                                                       ========
</TABLE>
- ---------

(1) Aggregate cost of securities listed under "Schedule of Investments" is
    based on their aggregate underlying value.

(2) An irrevocable letter of credit has been deposited with the Trustee as
    collateral, which is sufficient to cover the monies necessary for the pur-
    chase of the securities pursuant to contracts for the purchase of such se-
    curities.

(3) Represents the amount of mandatory distributions from the Portfolio
    ($0.195 per Unit), payable to the Sponsor in ten equal monthly install-
    ments of $0.0195 per Unit beginning on July 31, 2000, and on the last
    business day thereafter through April 30, 2001.

(4) A portion of the Public Offering Price consists of an amount sufficient to
    reimburse the Sponsor for all or a portion of the costs of establishing
    the Portfolio. These costs have been estimated at $.022 per Unit for the
    Portfolio. A payment will be made as of the earlier of six months after
    the Initial Date of Deposit or the end of the initial offering period to
    an account maintained by the Trustee from which the obligations of the in-
    vestors to the Sponsor will be satisfied. To the extent that actual organ-
    ization costs are greater than the estimated amount, only the estimated
    organization costs added to the Public Offering Price will be reimbursed
    to the Sponsor and deducted from the assets of the Portfolio.

(5) Aggregate Public Offering Price computed as set forth under "PUBLIC OFFER-
    ING PRICE" in Part B of this Prospectus.

(6) The gross underwriting commission of 2.95% per Unit includes both an
    Upfront and a Deferred Sales Charge and has been calculated on the assump-
    tion that the Units sold are not subject to a reduction of sales charges
    for quantity purchases. In single transactions involving 5,000 Units or
    more, the sales charge is reduced. (See "PUBLIC OFFERING PRICE" in Part B
    of this Prospectus.)


                                      ---
                                      11
<PAGE>

Report of Independent Public Accountants

To the Board of Directors of John Nuveen & Co. Incorporated and Unitholders of
Nuveen Unit Trusts, Series 91:

We have audited the accompanying statement of condition and the schedule of
investments at date of deposit (included in Part A of this Prospectus) of
Nuveen Unit Trusts, Series 91 as of May 15, 2000. These financial statements
are the responsibility of the Sponsor. Our responsibility is to express an
opinion on these financial statements based on our audit.

We conducted our audit in accordance with auditing standards generally ac-
cepted in the United States. Those standards require that we plan and perform
the audit to obtain reasonable assurance about whether the financial state-
ments are free of material misstatement. An audit includes examining, on a
test basis, evidence supporting the amounts and disclosures in the financial
statements. Our procedures included confirmation of the irrevocable letter of
credit arrangement for the purchase of securities, described in Note (2) to
the statement of condition, by correspondence with the Trustee. An audit also
includes assessing the accounting principles used and significant estimates
made by the Sponsor, as well as evaluating the overall financial statement
presentation. We believe that our audit provides a reasonable basis for our
opinion.

In our opinion, the statement of condition and the schedule of investments at
date of deposit referred to above present fairly, in all material respects,
the financial position of Nuveen Unit Trusts, Series 91, as of May 15, 2000,
in conformity with accounting principles generally accepted in the United
States.

                                                ARTHUR ANDERSEN LLP

Chicago, Illinois

May 15, 2000

                                      ---
                                      12
<PAGE>





                 (This page has been left blank intentionally.)





                                      ---
                                       13
<PAGE>

[NUVEEN Defined Portfolios Logo]

                       NUVEEN UNIT TRUSTS, SERIES 91
                              PROSPECTUS -- PART A

                               May 15, 2000

                              Sponsor       John Nuveen & Co. Incorporated
                                            333 West Wacker Drive
                                            Chicago, IL 60606-1286
                                            Telephone: 312-917-7700


                              Trustee       The Chase Manhattan Bank
                                            4 New York Plaza
                                            New York, NY 10004-2413
                                            Telephone: 800-257-8787

  This Prospectus does not contain complete information about the Portfolios
filed with the Securities and Exchange Commission in Washington, DC under the:

  Securities Act of 1933 (file no. 333-36520)

  Investment Company Act of 1940 (file no. 811-08103)

  More information about the Trusts, including the code of ethics adopted by
the Sponsor and the Trusts, can be found in the Commission's Public Reference
Room. Information about the operation of the Public Reference Room may be ob-
tained by calling the Commission at 1-202-942-8090. Trust information is also
available on the EDGAR Database on the Commission's website at
http://www.sec.gov, or may be obtained at proscribed rates by sending an e-mail
request to [email protected] or by writing to the Commission's Public Refer-
ence Section at 450 Fifth Street NW, Washington, D.C 20549-0102.

  No person is authorized to give any information or representation about the
Portfolios not contained in Parts A or B of this Prospectus or the Information
Supplement, and you should not rely on any other information.

  When Units of a Portfolio are no longer available or for investors who will
reinvest into subsequent series of the Portfolio, this Prospectus may be used
as a preliminary Prospectus for a future series. If this is the case, investors
should note the following:

    1. Information in this Prospectus is not complete and may be changed;

    2. We may not sell these securities until the registration statement
  filed with the Securities and Exchange Commission is effective; and

    3. This Prospectus is not an offer to sell the securities of a future
  series and is not soliciting an offer to buy such securities in any state
  where the offer or sale is not permitted.


<PAGE>

[LOGO NUVEEN DEFINED PORTFOLIOS]

Nuveen Equity Portfolio Prospectus

         Prospectus Part B dated May 15, 2000

  The Prospectus for a Nuveen Defined Portfolio (a "Trust") is divided into two
parts. Part A of the Prospectus relates exclusively to a particular Trust or
Trusts and provides specific information regarding each Trust's portfolio,
strategies, investment objectives, expenses, financial highlights, income and
capital distributions, hypothetical performance information, risk factors and
optional features. Part B of the Prospectus provides more general information
regarding the Nuveen Defined Portfolios. You should read both Parts of the
Prospectus and retain them for future reference. Except as provided in Part A
of the Prospectus, the information contained in this Part B will apply to each
Trust.

  Additional information about the Trusts is provided in the Information
Supplement. You can receive an Information Supplement by calling The Chase
Manhattan Bank (the "Trustee") at (800) 257-8787.

Nuveen Defined Portfolios

Each Nuveen Defined Portfolio consists of a portfolio of Securities of
companies described in the applicable Part A of the Prospectus (see "Schedule
of Investments" in Part A of the Prospectus for a list of the Securities
included in a Trust).

Minimum Investment--$1,000 or 100 Units ($500 or nearest whole number of Units
whose value is less than $500 for IRA purchases), whichever is less.

Redeemable Units. Units of a Trust are redeemable at the offices of the Trustee
at prices based upon the aggregate underlying value of the Securities
(generally determined by the closing sale prices of listed Securities and the
bid prices of over-the-counter traded Securities). During the period ending
with the earlier of six months after the Initial Date of Deposit or the end of
the initial offering period, the Redemption Price per Unit includes estimated
organization costs per Unit. After such period, the Redemption Price will not
include such estimated organization costs. See "Risk/Return Summary--Fees and
Expenses" in Part A of the Prospectus for the organization costs and see
"REDEMPTION" herein for a more detailed discussion of redeeming your Units.

Dividend and Capital Distributions. Cash dividends received by a Trust will be
paid on those dates set forth under "Distributions" in Part A of the
Prospectus. Distributions of funds in the Capital Account, if any, will be made
as part of the final liquidation distribution, if applicable, and in certain
circumstances, earlier. See "DISTRIBUTIONS TO UNITHOLDERS."

Public Offering Price. Public Offering Price of a Trust during the Initial
Offering Period is based upon the aggregate underlying value of the Securities
in the Trust's portfolio (generally determined by the closing sale prices of
the listed Securities and the ask prices of over-the-counter traded Securities)
plus or minus cash, if any, in the Income and Capital Accounts of the Trust,
plus a sales charge as set forth in Part A of the Prospectus and is rounded to
the nearest cent. The Public Offering Price during the period ending with the
earlier of six months after the Initial Date of Deposit or the end of the
initial offering period also includes organization costs incurred in
establishing a Trust. These costs will be deducted from the assets of the Trust
as of the close of such period. See "Risk/Return Summary-Fees and Expenses" in
Part A of the Prospectus. For Units purchased in the secondary market, the
Public Offering Price is based upon the aggregate underlying value of the
Securities in the Trust (generally determined by the closing sale prices of the
listed Securities and the bid prices of over-the-counter traded Securities)
plus the applicable sales charges. A pro rata share of accumulated dividends,
if any, in the Income Account from the preceding Record Date to, but not
including, the settlement date (normally three business days after purchase) is
added to the Public Offering Price. (See "PUBLIC OFFERING PRICE.")

  The Securities and Exchange Commission has not approved or disapproved these
securities or passed upon the adequacy of this prospectus. Any representation
to the contrary is a criminal offense.
<PAGE>

                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                            Page
                                                                            ----
<S>                                                                         <C>
NUVEEN DEFINED PORTFOLIOS..................................................   3
COMPOSITION OF TRUSTS......................................................   4
PUBLIC OFFERING PRICE......................................................   6
MARKET FOR UNITS...........................................................   9
EVALUATION OF SECURITIES AT THE INITIAL DATE OF DEPOSIT....................  10
TAX STATUS.................................................................  10
RETIREMENT PLANS...........................................................  15
TRUST OPERATING EXPENSES...................................................  15
DISTRIBUTIONS TO UNITHOLDERS...............................................  16
ACCUMULATION PLAN..........................................................  17
REPORTS TO UNITHOLDERS.....................................................  18
UNIT VALUE AND EVALUATION..................................................  18
DISTRIBUTIONS OF UNITS TO THE PUBLIC.......................................  19
OWNERSHIP AND TRANSFER OF UNITS............................................  21
REPLACEMENT OF LOST, STOLEN OR DESTROYED CERTIFICATES......................  21
REDEMPTION.................................................................  21
SPECIAL REDEMPTION, LIQUIDATION AND INVESTMENT IN A NEW TRUST..............  23
PURCHASE OF UNITS BY THE SPONSOR...........................................  25
REMOVAL OF SECURITIES FROM THE TRUSTS......................................  25
INFORMATION ABOUT THE TRUSTEE..............................................  26
LIMITATIONS ON LIABILITIES OF SPONSOR AND TRUSTEE..........................  26
SUCCESSOR TRUSTEES AND SPONSORS............................................  26
INFORMATION ABOUT THE SPONSOR..............................................  27
INFORMATION ABOUT THE EVALUATOR............................................  27
FORTUNE LICENSE AGREEMENT..................................................  28
OTHER INFORMATION..........................................................  28
LEGAL OPINION..............................................................  29
AUDITORS...................................................................  29
CODE OF ETHICS.............................................................  29
SUPPLEMENTAL INFORMATION...................................................  29
</TABLE>

                                       2
<PAGE>

Nuveen Defined Portfolios

  This Nuveen Defined Portfolio is one of a series of separate but similar
investment companies created by John Nuveen & Co. Incorporated, each of which
is designated by a different Series number. The Nuveen Defined Portfolios
consist of, among others, Strategy Trusts and Sector Trusts. Strategy Trusts
include, but are not limited to, Nuveen-Standard & Poor's Quality Buyback
Portfolios, Nuveen Dow 5SM and Dow 10SM Portfolios, Nuveen Legacy Portfolios,
Nuveen Rittenhouse Concentrated Growth Portfolios, Nuveen-FORTUNE's America's
Most Admired Companies Portfolios, Arvest Regional ImpactTM Portfolios, Harris
Insight(R) Multi-Sector Portfolios, Dorsey, Wright Relative Strength 5
Portfolios, Peroni Top Ten Picks Portfolios and Peroni Growth Portfolios.
Sector Trusts include, but are not limited to, Nuveen Energy Sector
Portfolios, Nuveen Financial Services Sector Portfolios, Nuveen Pharmaceutical
Sector Portfolios, Nuveen Precious Metals Sector Portfolios, Nuveen Technology
Sector Portfolios, Nuveen Communications Sector Portfolios, Nuveen Bandwidth
Sector Portfolios, Nuveen Consumer Electronics Sector Portfolios, Nuveen
Digital Sector Portfolios, Nuveen e-Commerce Sector Portfolios, Nuveen e-
Finance Sector Portfolios, Nuveen Internet Sector Portfolios, Nuveen Retail
Sector Portfolios, Nuveen Semiconductor Sector Portfolios, Nuveen Utility
Sector Portfolios, Nuveen Wireless Sector Portfolios, Nuveen e-Business Sector
Portfolios, Nuveen Glass-Steagall Sector Portfolios, Nuveen i-Media &
Advertising Sector Portfolios, Nuveen Networking & Storage Sector Portfolios,
Nuveen Software Weblications Sector Portfolios, Nuveen Pharmaceutical Sector
Portfolios and Nuveen Fuel Cell Sector Portfolios. Additional Series of the
Nuveen Defined Portfolios are the Nuveen Nasdaq-100 Growth and Treasury
Portfolios.

  The underlying unit investment trusts contained in this Series are combined
under one Trust Indenture and Agreement. Specific information regarding each
Trust is set forth in Part A of this Prospectus. The various Nuveen Defined
Portfolios are collectively referred to herein as the "Trusts."  This Series
was created under the laws of the State of New York pursuant to a Trust
Indenture and Agreement dated the Initial Date of Deposit (the "Indenture")
between John Nuveen & Co. Incorporated ("Nuveen" or the "Sponsor") and The
Chase Manhattan Bank (the "Trustee").

  The Sponsor has deposited with the Trustee delivery statements relating to
contracts for the purchase of the securities of the companies described in the
applicable Part A of the Prospectus, together with funds represented by an
irrevocable letter of credit issued by a major commercial bank in the amount
required for their purchase (or the securities themselves). See "Schedule of
Investments" in Part A of the Prospectus, for a description of the Securities
deposited in the applicable Trust. See also, "Risk/Return Summary" and "Risk
Factors" in Part A of the Prospectus. As used herein, the term "Securities"
means the Securities (including contracts for the purchase thereof) initially
deposited in each Trust and described in the related portfolio and any
additional equity securities that may be held by a Trust.

  The Trustee has delivered to the Sponsor registered Units which represent
ownership of the entire Trust, and which are offered for sale by this
Prospectus. Each Unit of a Trust represents a fractional undivided interest in
the Securities deposited in such Trust. Units may only be sold in states in
which they are registered. To the extent that any Units of any Trust are
redeemed by the Trustee, the aggregate value of the Trust's assets will
decrease by the amount paid to the redeeming Unitholder, but the fractional
undivided interest of each unredeemed Unit in such Trust will increase
proportionately. The Sponsor will initially, and from time to time thereafter,
hold Units in connection with their offering.

  Additional Units of a Trust may be issued from time to time following the
Initial Date of Deposit by depositing in such Trust additional Securities (or
contracts therefore backed by an irrevocable letter of credit or cash) or cash
(including a letter of credit) with instructions to purchase additional
Securities in the Trust. As additional Units are issued by a Trust as a result
of the deposit of additional Securities or cash by the Sponsor, the aggregate
value of the Securities in a Trust will be increased and the fractional
undivided interest in such Trust represented by each Unit will be decreased.
The Sponsor may continue to make additional deposits of Securities, or cash
with instructions to purchase additional Securities, into a Trust following
the Initial Date of Deposit, provided that such additional deposits will be in
amounts which will maintain, within reasonable parameters, the same original
proportionate relationship among the Securities in such Trust established on
the Initial Date of Deposit. Thus, although

                                       3
<PAGE>

additional Units will be issued, each Unit will continue to represent the same
proportionate amount of each Security. To the extent that any Units are
redeemed by the Trustee or additional Units are issued as a result of
additional Securities or cash being deposited by the Sponsor, the fractional
undivided interest in a Trust represented by each unredeemed Unit will
decrease or increase accordingly, although the actual interest in such Trust
represented by such fraction will remain unchanged. If the Sponsor deposits
cash, however, existing and new investors may experience a dilution of their
investment and a reduction in their anticipated income because of fluctuations
in the price of the Securities between the time of the cash deposit and the
purchase of the Securities and because the Trust will pay the associated
brokerage fees. To minimize this effect, the Trust will try to purchase the
Securities as close to the evaluation time or as close to the evaluation price
as possible. Units will remain outstanding until redeemed upon tender to the
Trustee by Unitholders, which may include the Sponsor, or until termination of
the Indenture.

  The Sponsor may realize a profit (or sustain a loss) as of the opening of
business on the Initial Date of Deposit resulting from the difference between
the purchase prices of the Securities and the cost of such Securities to the
Trust, which is based on the evaluation of the Securities as of the opening of
business on the Initial Date of Deposit. (See "Schedule of Investments" in
Part A of the Prospectus.) The Sponsor may also be considered to have realized
a profit or to have sustained a loss, as the case may be, in the amount of any
difference between the cost of the Securities to the Trust (which is based on
the Evaluator's determination of the aggregate value of the underlying
Securities of the Trust) on the subsequent date(s) of deposit and the cost of
such Securities to Nuveen, if applicable.

Composition of Trusts

  Each Trust initially consists of delivery statements relating to contracts
to purchase Securities (or of such Securities) as are listed under "Schedule
of Investments" in Part A of this Prospectus and, thereafter, of such
Securities as may continue to be held from time to time (including certain
securities deposited in the Trust to create additional Units or in
substitution for Securities not delivered to a Trust). To assist the Sponsor
in selecting Securities for certain Trusts, the Sponsor may use its own
resources to pay outside research service providers.

  Limited Replacement of Certain Securities. Neither the Sponsor nor the
Trustee shall be liable in any way for any default, failure or defect in any
Security. In the event of a failure to deliver any Security that has been
purchased for a Trust under a contract, including those Securities purchased
on a when, as and if issued basis ("Failed Securities"), the Sponsor is
authorized under the Indenture to direct the Trustee to acquire other
specified Securities ("Replacement Securities") to make up the original corpus
of the Trust within 20 days after delivery of notice of the failed contract
and the cost to the Trust may not exceed the amount of funds reserved for the
purchase of the Failed Securities.

  If the right of limited substitution described in the preceding paragraph is
not utilized to acquire Replacement Securities in the event of a failed
contract, the Sponsor will refund the sales charge attributable to such Failed
Securities to all Unitholders of the Trust and the Trustee will distribute the
principal attributable to such Failed Securities not more than 120 days after
the date on which the Trustee received a notice from the Sponsor that a
Replacement Security would not be deposited in the Trust. In addition,
Unitholders should be aware that, at the time of receipt of such principal,
they may not be able to reinvest such proceeds in other securities with
equivalent growth potential at a comparable price.

  The Indenture also authorizes the Sponsor to increase the size of the Trust
and the number of Units thereof by the deposit of additional Securities in the
Trust or cash (including a letter of credit) with instructions to purchase
additional Securities in the Trust and the issuance of a corresponding number
of additional Units. If the Sponsor deposits cash, however, existing and new
investors may experience a dilution of their investment and a reduction in
their anticipated income because of fluctuations in the

                                       4
<PAGE>

prices of the Securities between the time of the cash deposit and the purchase
of the Securities and because the Trust will pay the associated brokerage
fees.

  Sale of Securities. Certain of the Securities may from time to time under
certain circumstances be sold. The proceeds from such events will be used to
pay for expenses or for Units redeemed or distributed to Unitholders and not
reinvested; accordingly, no assurance can be given that a Trust will retain
for any length of time its present size and composition.

  Whether or not the Securities are listed on a securities exchange, the
principal trading market for the Securities may be in the over-the-counter
market. As a result, the existence of a liquid trading market for the
Securities may depend on whether dealers will make a market in the Securities.
There can be no assurance that a market will be made for any of the
Securities, that any market for the Securities will be maintained or of the
liquidity of the Securities in any markets made. In addition, the Trust may be
restricted under the Investment Company Act of 1940 from selling Securities to
the Sponsor. The price at which the Securities may be sold to meet redemptions
and the value of a Trust will be adversely affected if trading markets for the
Securities are limited or absent. There can be no assurance that a Trust or,
if applicable, successive trusts that employ the same or a similar investment
strategy, will achieve their investment objectives.

  Legislation. At any time after the Initial Date of Deposit, legislation may
be enacted, with respect to the Securities in a Trust or the issuers of the
Securities. Changing approaches to regulation, particularly with respect to
the environment or with respect to the petroleum or tobacco industry, may have
a negative impact on certain companies represented in a Trust. There can be no
assurance that future legislation, regulation or deregulation will not have a
material adverse effect on a Trust or will not impair the ability of the
issuers of the Securities to achieve their business goals.

  Unitholders will be unable to dispose of any of the Securities in a Trust
and will not be able to vote the Securities. As the holder of the Securities,
the Trustee will have the right to vote all of the voting stocks in a Trust
and will vote such stocks in accordance with the instructions of the Sponsor.

  Litigation. Except as provided in Part A of the Prospectus, to the best
knowledge of the Sponsor, there is no litigation pending as of the Initial
Date of Deposit in respect of any Securities which might reasonably be
expected to have a material adverse effect on any of the Trusts. It is
possible that after the Initial Date of Deposit, litigation may be initiated
with respect to Securities in any Trust or current litigation may have
unexpected results. The Sponsor is unable to predict whether any such
litigation may have such results or may be instituted, or if instituted,
whether any such litigation might have a material adverse effect on the
Trusts.

                                       5
<PAGE>

Public Offering Price

  The Public Offering Price of the Units is based on the aggregate underlying
value of the Securities in the Trust (generally determined by the closing sale
prices of listed Securities and the ask prices of over-the-counter traded
Securities), plus or minus cash, if any, in the Income and Capital Accounts of
the Trust, plus an initial sales charge equal to the difference between the
maximum sales charge (as set forth in Part A of the Prospectus) per Unit and
the maximum remaining deferred sales charge (as set forth in Part A of the
Prospectus) and is rounded to the nearest cent. In addition, a portion of the
Public Offering Price during the initial offering period also consists of
Securities in an amount sufficient to pay for all or a portion of the costs
incurred in establishing a Trust, including costs of preparing the
registration statement, the trust indenture and other closing documents,
registering Units with the Securities and Exchange Commission and states, the
initial audit of each Trust portfolio, the initial evaluation, legal fees, the
initial fees and expenses of the Trustee and any non-material out-of-pocket
expenses.

  The Securities purchased with the portion of the Public Offering Price
intended to be used to reimburse the Sponsor for the Trust's organization
costs will be purchased in the same proportionate relationship as all the
Securities contained in the Trust. Securities will be sold to reimburse the
Sponsor for the Trust's organization costs at the earlier of six months after
the Initial Date of Deposit or the end of the initial offering period (a
shorter time period than the life of the Trust). During the period ending with
the earlier of six months after the Initial Date of Deposit or the end of the
initial offering period, there may be a decrease in the value of the
Securities. To the extent the proceeds from the sale of these Securities are
insufficient to repay the Sponsor for the Trust organization costs, the
Trustee will sell additional Securities to allow the Trust to fully reimburse
the Sponsor. In that event, the net asset value per Unit will be reduced by
the amount of additional Securities sold. Although the dollar amount of the
reimbursement due to the Sponsor will remain fixed and will never exceed the
amount per Unit set forth for the Trusts in "Statement of Condition," this
will result in a greater effective cost per Unit to Unitholders for the
reimbursement to the Sponsor. When Securities are sold to reimburse the
Sponsor for organization costs, the Trustee will sell such Securities to an
extent which will maintain the same proportionate relationship among the
Securities contained in the Trust as existed prior to such sale. See
"Risk/Return Summary--Fees and Expenses" in Part A of the Prospectus.

  Commencing on those dates set forth under "Risk/Return Summary--Fees and
Expenses" in Part A of this Prospectus, a deferred sales charge in an amount
described in Part A of the Prospectus will be assessed per Unit per applicable
month. The deferred sales charges will be paid from funds in the Capital
Account, if sufficient, or from the periodic sale of Securities. A pro rata
share of accumulated dividends, if any, in the Income Account from the
preceding Record Date to, but not including, the settlement date (normally
three business days after purchase) is added to the Public Offering Price. The
total maximum sales charge assessed to Unitholders on a per Unit basis will be
the amount set forth in "Risk/Return Summary--Fees and Expenses" in Part A of
the Prospectus. See "UNIT VALUE AND EVALUATION."

  The sales charge applicable to quantity purchases is reduced on a graduated
scale as set forth in Part A of this Prospectus. For purposes of calculating
the applicable sales charge, purchasers who have indicated their intent to
purchase a specified amount of Units of any Nuveen unit investment trust in
the primary or secondary offering period by executing and delivering a letter
of intent to the Sponsor, which

                                       6
<PAGE>

letter of intent must be in a form acceptable to the Sponsor and shall have a
maximum duration of thirteen months, will be eligible to receive a reduced
sales charge according to the graduated scale provided in Part A of this
Prospectus, based on the amount of intended aggregate purchases (excluding
purchases which are subject only to a deferred sales charge) as expressed in
the letter of intent. For purposes of letter of intent calculations, units of
equity-based products are valued at $10 per unit. Due to administrative
limitations and in order to permit adequate tracking, the only secondary
market purchases that will be permitted to be applied toward the intended
specified amount and that will receive the corresponding reduced sales charge
are those Units that are acquired through or from the Sponsor. By establishing
a letter of intent, a Unitholder agrees that the first purchase of Units
following the execution of such letter of intent will be at least 5% of the
total amount of the intended aggregate purchases expressed in such
Unitholder's letter of intent. Further, through the establishment of the
letter of intent, such Unitholder agrees that Units representing 5% of the
total amount of the intended purchases will be held in escrow by the Trustee
pending completion of these purchases. All distributions on Units held in
escrow will be credited to such Unitholder's account. If total purchases prior
to the expiration of the letter of intent period equal or exceed the amount
specified in a Unitholder's letter of intent, the Units held in escrow will be
transferred to such Unitholder's account. A Unitholder who purchases Units
during the letter of intent period in excess of the number of Units specified
in a Unitholder's letter of intent, the amount of which would cause the
Unitholder to be eligible to receive an additional sales charge reduction,
will be allowed such additional sales charge reduction on the purchase of
Units which caused the Unitholder to reach such new breakpoint level and on
all additional purchases of Units during the letter of intent period. If the
total purchases are less than the amount specified, the Unitholder involved
must pay the Sponsor an amount equal to the difference between the amounts
paid for these purchases and the amounts which would have been paid if the
higher sales charge had been applied; the Unitholder will, however, be
entitled to any reduced sales charge qualified for by reaching any lower
breakpoint level. If such Unitholder does not pay the additional amount within
20 days after written request by the Sponsor or the Unitholder's securities
representative, the Sponsor will instruct the Trustee to redeem an appropriate
number of the escrowed Units to meet the required payment. By establishing a
letter of intent, a Unitholder irrevocably appoints the Sponsor as attorney to
give instructions to redeem any or all of such Unitholder's escrowed Units,
with full power of substitution in the premises. A Unitholder or his
securities representative must notify the Sponsor whenever such Unitholder
makes a purchase of Units that he wishes to be counted towards the intended
amount.

  For "secondary market" sales, the Public Offering Price is based on the
aggregate underlying value of the Securities in a Trust as of the Evaluation
Time (generally determined by the closing sale prices of listed Securities and
the bid prices of over-the-counter traded Securities), plus or minus cash, if
any, in the Income and Capital Accounts of a Trust, plus an initial sales
charge equal to the difference between the maximum sales charge and any
remaining deferred sales charges. The maximum sales charge for certain trusts
is described in Part A of the Prospectus. See "UNIT VALUE AND EVALUATION."

  In the secondary market for Nuveen Five-Year Sector Portfolios, Legacy Five-
Year Portfolios and Arvest Regional ImpactTM Portfolios, prior to the
completion of the deferred sales charge period, the maximum sales charge will
be 4.50% of the Public Offering Price. The upfront portion of the sales charge
will equal the difference between 4.5% of the Public Offering Price and any
remaining deferred sales charges. Unitholders that purchase more than 5,000
Units and certain classes of investors are entitled to purchase Units at
reduced sales charges as shown below.

<TABLE>
<CAPTION>
                                                                       Total
                                                                      Maximum
        Number of Units                                             Sales Charge
        ---------------                                             ------------
        <S>                                                         <C>
        Less than 5,000............................................     4.50%
        5,000 to 9,999.............................................     4.25%
        10,000 to 24,999...........................................     4.00%
        25,000 to 49,999...........................................     3.50%
        50,000 to 99,999...........................................     2.50%
        100,000 or more............................................     1.50%
        Wrap and Trust Account Purchases...........................     1.00%
</TABLE>

                                       7
<PAGE>

  For secondary market sales after the completion of the deferred sales charge
period for Nuveen Five-Year Sector Portfolios and Arvest Regional ImpactTM
Portfolios, the maximum sales charge will be a one-time charge of 4.5% of the
Public Offering Price. Unitholders that purchase more than 5,000 Units and
certain classes of investors are entitled to purchase Units at reduced sales
charges shown below. Secondary market sales charges are reduced by 1/2 of 1%
on each subsequent July 31, commencing July 31, 2000, to a minimum sales
charge of 3.0% of the Public Offering Price as shown below with reduced sales
charges for larger purchases and certain investors:

<TABLE>
<CAPTION>
           Number of Units*                   Total Maximum Sales Charge
           ----------------               ------------------------------------------------------
                                          4.5%           4.0%           3.5%           3.0%
                                          ----           ----           ----           ----
   <S>                                    <C>            <C>            <C>            <C>
   Less than 5,000                        4.50           4.00           3.50           3.00
   5,000 to 9,999                         4.25           3.75           3.25           2.75
   10,000 to 24,999                       4.00           3.50           3.00           2.50
   25,000 to 49,999                       3.50           3.25           2.75           2.25
   50,000 to 99,999                       2.50           2.25           1.75           1.50
   100,000 or more                        1.50           1.25           1.00           0.75
   Wrap and Trust Account Purchases       1.00           1.00           1.00           1.00
</TABLE>
  --------
  * Sales charge reductions are computed both on a dollar basis and on
    the basis of the number of Units purchased, using the equivalent of
    5,000 Units to $50,000, 10,000 Units to $100,000, etc., and will be
    applied on that basis which is more favorable to Unitholders.
    All Units are subject to the same deferred sales charges. When the
    deferred charges exceed the maximum sales charge, Unitholders will
    be given extra Units at the time of purchase.

  Pursuant to the terms of the Indenture, the Trustee may terminate a Trust if
the net asset value of such Trust, as shown by any evaluation, is less than
20% of the total value of the Securities deposited in the Trust during the
primary offering period of the Trust.

  At all times while Units are being offered for sale, the Evaluator will
appraise or cause to be appraised daily the value of the underlying Securities
in each Trust as of 4:00 p.m. eastern time, or as of any earlier closing time
on a day on which the New York Stock Exchange (the "Exchange") is scheduled in
advance to close at such earlier time and will adjust the Public Offering
Price of the Units commensurate with such appraisal ("Evaluation Time"). Such
Public Offering Price will be effective for all orders received by a dealer or
the Sponsor at or prior to 4:00 p.m. eastern time on each such day or as of
any earlier closing time on a day on which the Exchange is scheduled in
advance to close at such earlier time. Orders received after that time, or on
a day when the Exchange is closed for a scheduled holiday or weekend, will be
held until the next determination of price.

  The graduated sales charges for the primary offering period set forth in the
table provided in Part A of this Prospectus will apply on all applicable
purchases of Nuveen investment company securities on any one day by the same
purchaser in the amounts stated, and for this purpose purchases of a Trust
will be aggregated with concurrent purchases of any other Nuveen unit
investment trust or of shares of any open-end management investment company of
which the Sponsor is principal underwriter and with respect to the purchase of
which a sales charge is imposed. Purchases by or for the account of
individuals and their spouses, parents, children, grandchildren, grandparents,
parents-in-law, sons- and daughters-in-law, siblings, a sibling's spouse and a
spouse's siblings ("immediate family members") will be aggregated to determine
the applicable sales charge. The graduated sales charges are also applicable
to a trustee or other fiduciary purchasing securities for a single trust
estate or single fiduciary account.

  Unitholders of other unit investment trusts having a similar strategy as the
Trust may utilize their termination proceeds to purchase Units of the Trusts
with the sales charge applicable for "Rollover Purchases" as provided in "How
to Buy and Sell Units" in Part A of the Prospectus. The dealer concession for
such purchases will be that applicable to "Rollover Purchases".

                                       8
<PAGE>

  Units may be purchased with the applicable reduced sales charge provided for
"Wrap Account Purchases" under "How to Buy and Sell Units" in Part A of the
Prospectus or herein by (1) investors who purchase Units through registered
investment advisers, certified financial planners and registered broker-
dealers who in each case either charge periodic fees for financial planning,
investment advisory services, brokerage services, investment services or asset
management services, or provide such services in connection with the
establishment of an investment account for which a comprehensive "wrap fee"
charge is imposed, (2) bank trust departments investing funds over which they
exercise discretionary investment authority and that are held in a fiduciary,
agency, custodial or similar capacity, (3) any person who for at least 90
days, has been an officer, director or bona fide employee of any firm offering
Units for sale to investors, (4) officers and directors of bank holding
companies that make Units available directly or through subsidiaries or bank
affiliates, and (5) officers or directors and bona fide, full-time employees
of Nuveen, Nuveen Advisory Corp., Nuveen Institutional Advisory Corp.,
Rittenhouse Financial Services, Inc., The John Nuveen Company, The McGraw Hill
Companies Inc. ("McGraw-Hill") and Dow Jones & Company, Inc. ("Dow Jones"),
including in each case these individuals and their spouses, children, parents
and spouses' parents, however, purchases by parents, individuals associated
with McGraw-Hill and Dow Jones, and adult children who are not members of the
household of the officers, directors or full-time employees described above,
must be made through a registered broker-dealer and (6) any person who for at
least 90 days, has been an officer, director or bona fide employee of any
vendor who provides services to the Sponsor and who purchases Units through a
registered broker-dealer (collectively, the "Discounted Purchases"). (For
individuals associated with McGraw Hill this privilege is only available for
purchases of Units of the Nuveen-Standard & Poor's Quality Buyback Portfolio
and for individuals associated with Dow Jones this privilege is only available
for purchases of Units of the Nuveen--The Dow 5sm Portfolio and the Nuveen--
The Dow 10sm Portfolio). Notwithstanding anything to the contrary in this
Prospectus, investors who purchase Units as described in this paragraph will
not receive sales charge reductions for quantity purchases.

  During the initial offering period, unitholders of any Nuveen-sponsored unit
investment trust may utilize their redemption or termination proceeds to
purchase Units of a Trust with the sales charge applicable for "Rollover
Purchases" as provided in "How to Buy and Sell Units" in Part A of the
Prospectus.

  Whether or not Units are being offered for sale, the Trustee will determine
or cause to be determined the aggregate value of each Trust as of 4:00 p.m.
eastern time: (i) on each June 30 or December 31 (or, if such date is not a
business day, the last business day prior thereto), (ii) on any day on which a
Unit is tendered for redemption (or the next succeeding business day if the
date of tender is a non-business day) and (iii) at such other times as may be
necessary. For this purpose, a "business day" shall be any day on which the
Exchange is normally open. (See "UNIT VALUE AND EVALUATION.")

Market for Units

  During the initial public offering period, the Sponsor intends to offer to
purchase Units of each Trust at a price based upon the pro rata share per Unit
of the aggregate underlying value of the Securities in such Trust as of the
Evaluation Time (generally determined by the closing sale prices of listed
Securities and the ask prices of over-the-counter traded Securities).
Afterward, although it is not obligated to do so, the Sponsor may maintain a
secondary market for Units of each Trust at its own expense and continuously
offer to purchase Units of each Trust at prices, subject to change at any
time, which are based upon the aggregate underlying value of the Securities in
a Trust as of the Evaluation Time (generally determined by the closing sale
prices of listed Securities and the bid prices of over-the-counter traded
Securities). During the period ending with the earlier of six months after the
Initial Date of Deposit or the end of the initial offering period, the price
at which the Sponsor expects to repurchase Units (the "Sponsor's Repurchase
Price") includes estimated organization costs per Unit. After such period, the
Sponsor's Repurchase Price will not include such estimated organization costs.
See "Risk/Return Summary--Fees and Expenses" in Part A of the Prospectus.
Unitholders who wish to dispose of their Units should inquire of the Trustee
or their broker as to the current Redemption Price. Units subject

                                       9
<PAGE>

to a deferred sales charge which are sold or tendered for redemption prior to
such time as the entire deferred sales charge on such Units has been collected
will be assessed the amount of the remaining deferred sales charge at the time
of sale or redemption. (See "REDEMPTION.")

  In connection with its secondary market making activities, the Sponsor may
from time to time enter into secondary market joint account agreements with
other brokers and dealers. Pursuant to such an agreement, the Sponsor will
generally purchase Units from the broker or dealer at the Redemption Price (as
defined in "REDEMPTION") and will place the Units into a joint account managed
by the Sponsor; sales from the account will be made in accordance with the
then current prospectus and the Sponsor and the broker or dealer will share
profits and losses in the joint account in accordance with the terms of their
joint account agreement.

  In maintaining a market for the Units, the Sponsor will realize profits or
sustain losses in the amount of any difference between the price at which
Units are purchased and the price at which Units are resold or redeemed. The
secondary market Public Offering Price of Units may be greater or less than
the cost of such Units to the Sponsor.

  Certificates, if any, for Units are delivered to the purchaser as promptly
after the date of settlement (three business days after purchase) as the
Trustee can complete the mechanics of registration, normally within 48 hours
after registration instructions are received. Purchasers of Units to whom
Certificates are issued will be unable to exercise any right of redemption
until they have received their Certificates, properly endorsed for transfer.
(See "REDEMPTION.")

Evaluation of Securities at the Initial Date of Deposit

  The prices of the Securities deposited in the Trusts included in Part A of
the Prospectus were determined by the Trustee.

  The amount by which the Trustee's determination of the aggregate value of
the Securities deposited in the Trusts was greater or less than the cost of
such Securities to the Sponsor was profit or loss to the Sponsor. (See Part A
of this Prospectus.) The Sponsor also may realize further profit or sustain
further loss as a result of fluctuations in the Public Offering Price of the
Units. Cash, if any, made available to the Sponsor prior to the settlement
date for a purchase of Units, or prior to the acquisition of all Portfolio
securities by a Trust, may be available for use in the Sponsor's business, and
may be of benefit to the Sponsor.

Tax Status

  The following is a general discussion of certain of the Federal income tax
consequences of the purchase, ownership and disposition of the Units. The
summary is limited to investors who hold the Units as "capital assets"
(generally, property held for investment) within the meaning of Section 1221
of the Internal Revenue Code of 1986 (the "Code"). Unitholders should consult
their tax advisers in determining the Federal, state, local and any other tax
consequences of the purchase, ownership and disposition of Units in a Trust.
For purposes of the following discussion and opinions, it is assumed that each
Security is equity for Federal income tax purposes.

                                      10
<PAGE>

  In the opinion of Chapman and Cutler, special counsel for the Sponsor, under
existing law:

    1. Each Trust is not an association taxable as a corporation for Federal
  income tax purposes; each Unitholder will be treated as the owner of a pro
  rata portion of each of the assets of the Trust under the Code; and the
  income of the Trust will be treated as income of the Unitholders thereof
  under the Code. Each Unitholder will be considered to have received his pro
  rata portion of income derived from each Trust asset when such income is
  considered to be received by the Trust. A Unitholder will be considered to
  have received all of the dividends paid on his pro rata portion of each
  Security when such dividends are considered to be received by the Trust
  regardless of whether such dividends are used to pay a portion of the
  deferred sales charge. Unitholders will be taxed in this manner regardless
  of whether distributions from the Trust are actually received by the
  Unitholder or are automatically reinvested.

    2. Each Unitholder will have a taxable event when a Trust disposes of a
  Security (whether by sale, taxable exchange, liquidation, redemption, or
  otherwise) or upon the sale or redemption of Units by such Unitholder
  (except to the extent an in-kind distribution of stock is received by such
  Unitholder as described below). The price a Unitholder pays for his or her
  Units, generally including sales charges, is allocated among his or her pro
  rata portion of each Security held by the Trust (in proportion to the fair
  market values thereof on the valuation date closest to the date the
  Unitholder purchases his or her Units) in order to determine his or her tax
  basis for his or her pro rata portion of each Security held by the Trust.
  Unitholders should consult their own tax advisors with regard to the
  calculation of basis. For Federal income tax purposes, a Unitholder's pro
  rata portion of dividends, as defined by Section 316 of the Code, paid by a
  corporation with respect to a Security held by the Trust is taxable as
  ordinary income to the extent of such corporation's current and accumulated
  "earnings and profits." A Unitholder's pro rata portion of dividends paid
  on such Security which exceeds such current and accumulated earnings and
  profits will first reduce a Unitholder's tax basis in such Security, and to
  the extent that such dividends exceed a Unitholder's tax basis in such
  Security shall generally be treated as capital gain. In general, the
  holding period for such capital gain will be determined by the period of
  time a Unitholder has held his or her Units.

    3. A Unitholder's portion of gain, if any, upon the sale or redemption of
  Units or the disposition of Securities held by the Trust will generally be
  considered a capital gain (except in the case of a dealer or a financial
  institution). A Unitholder's portion of loss, if any, upon the sale or
  redemption of Units or the disposition of Securities held by the Trust will
  generally be considered a capital loss (except in the case of a dealer or a
  financial institution). Unitholders should consult their tax advisors
  regarding the recognition of such capital gains and losses for Federal
  income tax purposes. In particular, a Rollover Unitholder should be aware
  that a Rollover Unitholder's loss, if any, incurred in connection with the
  exchange of Units for units in the next new series of a Trust (the "New
  Trust"), (if so provided in Part A of the Prospectus, the Sponsor intends
  to create a separate New Trust in conjunction with the termination of the
  Trust) will generally be disallowed with respect to the disposition of any
  Securities pursuant to such exchange to the extent that such Unitholder is
  considered the owner of substantially identical securities under the wash
  sale provisions of the Code taking into account such Unitholder's deemed
  ownership of the securities underlying the Units in the New Trust in the
  manner described above, if such substantially identical securities are
  acquired within a period beginning 30 days before and ending 30 days after
  such disposition. However, any gains incurred in connection with such an
  exchange by a Rollover Unitholder would be recognized. Unitholders should
  consult their tax advisers regarding the recognition of gains and losses
  for Federal income tax purposes.

  Deferred Sales Charge. Generally the tax basis of a Unitholder includes
sales charges, and such charges are not deductible. A portion of the sales
charge is deferred. The income (or proceeds from redemption) a Unitholder must
take into account for Federal income tax purposes is not reduced by amounts
deducted to pay the deferred sales charge. Unitholders should consult their
own tax advisers as to the income tax consequences of the deferred sales
charge.

                                      11
<PAGE>

  Dividends Received Deduction. A corporation that owns Units will generally
be entitled to a 70% dividends received deduction with respect to such
Unitholder's pro rata portion of dividends received by the Trust (to the
extent such dividends are taxable as ordinary income, as discussed above and
are attributable to domestic corporations) in the same manner as if such
corporation directly owned the Securities paying such dividends (other than
corporate Unitholders, such as "S" corporations, which are not eligible for
the deduction because of their special characteristics and other than for
purposes of special taxes such as the accumulated earnings tax and the
personal holding corporation tax). However, a corporation owning Units should
be aware that Sections 246 and 246A of the Code impose additional limitations
on the eligibility of dividends for the 70% dividends received deduction.
These limitations include a requirement that stock (and therefore Units) must
generally be held at least 46 days (as determined under and during the period
specified in Section 246(c) of the Code). Final regulations have been issued
which address special rules that must be considered in determining whether the
46-day holding period requirement is met. Moreover, the allowable percentage
of the deduction will be reduced from 70% if a corporate Unitholder owns
certain stock (or Units) the financing of which is directly attributable to
indebtedness incurred by such corporation.

  To the extent dividends received by a Trust are atrributable to foreign
corporations, a corporation that owns Units will not be entitled to the
dividends received deduction with respect to its pro rata portion of such
dividends, since the dividends received deduction is generally available only
with respect to dividends paid by domestic corporations. Unitholders should
consult with their tax advisers with respect to the limitations on and
possible modifications to the dividends received deduction.

  Limitations on Deductibility of Trust Expenses by Unitholders. Each
Unitholder's pro rata share of each expense paid by a Trust is deductible by
the Unitholder to the same extent as though the expense had been paid directly
by him or her. As a result of the Tax Reform Act of 1986, certain
miscellaneous itemized deductions, such as investment expenses, tax return
preparation fees and employee business expenses will be deductible by an
individual only to the extent they exceed 2% of such individual's adjusted
gross income. Unitholder's may be required to treat some or all of the
expenses of a Trust as miscellaneous itemized deductions subject to this
limitation. Unitholders should consult with their tax advisers regarding the
limitations on the deductibility of Trust expenses.

  Recognition of Taxable Gain or Loss Upon Disposition of Securities by a
Trust or Disposition of Units. As discussed above, a Unitholder may recognize
taxable gain (or loss) when a Security is disposed of by the Trust or if the
Unitholder disposes of a Unit (although losses incurred by Rollover
Unitholders may be subject to disallowance, as discussed above). The Internal
Revenue Service Restructuring and Reform Act of 1998 (the "1998 Tax Act")
provides that for taxpayers other than corporations, net capital gain (which
is defined as net long-term capital gain over net short-term capital loss for
the taxable year) realized from property (with certain exclusions) is subject
to a maximum marginal stated tax rate of 20% (10% in the case of certain
taxpayers in the lowest tax bracket). Capital gain or loss is long-term if the
holding period for the asset is more than one year, and is short-term if the
holding period for the asset is one year or less. The date on which a Unit is
acquired (i.e., the "trade date") is excluded for purposes of determining the
holding period of the Unit. Capital gains realized from assets held for one
year or less are taxed at the same rates as ordinary income.

  In addition, please note that capital gains may be recharacterized as
ordinary income in the case of certain financial transactions that are
considered "conversion transactions" effective for transactions entered into
after April 30, 1993. Unitholders and prospective investors should consult
with their tax advisers regarding the potential effect of this provision on
their investment in Units.

  If the Unitholder disposes of a Unit, the Unitholder is deemed thereby to
have disposed of his or her entire pro rata interest in all assets of the
Trust involved including his or her pro rata portion of all the Securities
represented by the Unit.

                                      12
<PAGE>

  The Taxpayer Relief Act of 1997 (the "1997 Act") includes provisions that
treat certain transactions designed to reduce or eliminate risk of loss and
opportunities for gain (e.g., short sales, offsetting notional principal
contracts, futures or forward contracts or similar transactions) as
constructive sales for purposes of recognition of gain (but not loss) and for
purposes of determining the holding period. Unitholders should consult their
own tax advisors with regard to any such constructive sales rules.

  Special Tax Consequences of In-Kind Distributions Upon Redemption of Units,
Termination of a Trust and Investment in a New Trust. As discussed in
"REDEMPTION" and "OTHER INFORMATION--Termination of Indenture," under certain
circumstances a Unitholder who owns the number of Units of a Trust set forth
in Part A of the Prospectus may request an In-Kind Distribution upon the
redemption of Units or the termination of such Trust. The Unitholder
requesting an In-Kind Distribution will be liable for expenses related thereto
(the "Distribution Expenses") and the amount of such In-Kind Distribution will
be reduced by the amount of the Distribution Expenses. See "DISTRIBUTIONS TO
UNITHOLDERS." As previously discussed, prior to the redemption of Units or the
termination of a Trust, a Unitholder is considered as owning a pro rata
portion of each of the Trust's assets for Federal income tax purposes. The
receipt of an In-Kind Distribution upon the redemption of Units or the
termination of a Trust will result in a Unitholder receiving whole shares of
stock plus, possibly, cash.

  The potential tax consequences that may occur under an In-Kind Distribution
will depend on whether or not a Unitholder receives cash in addition to
Securities. A "Security" for this purpose is a particular class of stock
issued by a particular corporation. A Unitholder will not recognize gain or
loss if a Unitholder only receives Securities in exchange for his or her pro
rata portion in the Securities held by the Trust. However, if a Unitholder
also receives cash in exchange for a fractional share of a Security held by
the Trust, such Unitholder will generally recognize gain or loss based upon
the difference between the amount of cash received by the Unitholder and his
or her tax basis in such fractional share of a Security held by the Trust.

  Because each Trust will own many Securities, a Unitholder who requests an
In-Kind Distribution will have to analyze the tax consequences with respect to
each Security owned by the Trust. The amount of taxable gain (or loss)
recognized upon such exchange will generally equal the sum of the gain (or
loss) recognized under the rules described above by such Unitholder with
respect to each Security owned by the Trust. Unitholders who request an In-
Kind Distribution are advised to consult their tax advisers in this regard.

  As discussed in "SPECIAL REDEMPTION, LIQUIDATION AND INVESTMENT IN A NEW
TRUST," a Unitholder may elect to become a Rollover Unitholder. To the extent
a Rollover Unitholder exchanges his or her Units for Units of the New Trust in
a taxable transaction, such Unitholder will recognize gains, if any, but
generally will not be entitled to a deduction for any losses recognized upon
the disposition of any Securities pursuant to such exchange to the extent that
such Unitholder is considered the owner of substantially identical securities
under the wash sale provisions of the Code taking into account such
Unitholder's deemed ownership of the securities underlying the Units in the
New Trust in the manner described above, if such substantially identical
securities were acquired within a period beginning 30 days before and ending
30 days after such disposition under the wash sale provisions contained in
Section 1091 of the Code. In the event a loss is disallowed under the wash
sale provisions, special rules contained in Section 1091(d) of the Code apply
to determine the Unitholder's tax basis in the securities acquired. Rollover
Unitholders are advised to consult their tax advisers.

  Computation of the Unitholder's Tax Basis. Initially, a Unitholder's tax
basis in his or her Units will generally equal the price paid by such
Unitholder for his or her Units. The cost of the Units is allocated among the
Securities held by the Trust in accordance with the proportion of the fair
market values of such Securities on the valuation date nearest the date the
Units are purchased in order to determine such Unitholder's tax basis for his
or her pro rata portion of each Security.

                                      13
<PAGE>

  A Unitholder's tax basis in his or her Units and his or her pro rata portion
of a Security held by a Trust will be reduced to the extent dividends paid
with respect to such Security are received by the Trust which are not taxable
as ordinary income as described above.

  General. Each Unitholder will be requested to provide the Unitholder's
taxpayer identification number to the Trustee and to certify that the
Unitholder has not been notified that payments to the Unitholder are subject
to back-up withholding. If the proper taxpayer identification number and
appropriate certification are not provided when requested, distributions by
the Trust to such Unitholder (including amounts received upon the redemption
of Units) will be subject to back-up withholding. Distributions by the Trust
(other than those that are not treated as United States source income, if any)
will generally be subject to United States income taxation and withholding in
the case of Units held by non-resident alien individuals, foreign corporations
or other non-United States persons. Such persons should consult their tax
advisers.

  In general, income that is not effectively connected to the conduct of a
trade or business within the United States that is earned by non-U.S.
Unitholders and derived from dividends of foreign corporations will not be
subject to U.S. withholding tax provided that less than 25 percent of the
gross income of the foreign corporation for a three-year period ending with
the close of its taxable year preceding the year of payment was effectively
connected to the conduct of a trade or business within the United States. In
addition, such earnings may be exempt from U.S. withholding pursuant to a
specific treaty between the United States and a foreign country. Non-U.S.
Unitholders should consult their own tax advisers regarding the imposition of
U.S. withholding on distributions from the Trust.

  It should be noted that payments to a Trust of dividends on Securities that
are attributable to foreign corporations may be subject to foreign withholding
taxes and Unitholders should consult their tax advisers regarding the
potential tax consequences relating to the payment of any such withholding
taxes by a Trust. Any dividends withheld as a result thereof will nevertheless
be treated as income to the Unitholders. Because under the grantor trust
rules, an investor is deemed to have paid directly his share of foreign taxes
that have been paid or accrued, if any, an investor may be entitled to a
foreign tax credit or deduction for United States tax purposes with respect to
such taxes. A required holding period is imposed for such credits. Investors
should consult their tax advisers with respect to foreign withholding taxes
and foreign tax credits.

  At the termination of a Trust, the Trustee will furnish to each Unitholder a
statement containing information relating to the dividends received by the
Trust on the Securities, the gross proceeds received by the Trust from the
disposition of any Security (resulting from redemption or the sale of any
Security) and the fees and expenses paid by the Trust. The Trustee will also
furnish annual information returns to Unitholders and the Internal Revenue
Service.

  Unitholders desiring to purchase Units for tax-deferred plans and IRAs
should consult their broker for details on establishing such accounts. Units
may also be purchased by persons who already have self-directed plans
established. See "RETIREMENT PLANS."

  In the opinion of Carter, Ledyard & Milburn, Special Counsel to the Trusts
for New York tax matters, under the existing income tax laws of the State of
New York, each Trust is not an association taxable as a corporation and the
income of each Trust will be treated as the income of the Unitholders thereof.

  The foregoing discussion relates only to the tax treatment of U.S.
Unitholders ("U.S. Unitholder") with regard to federal and certain aspects of
New York State and City income taxes. Unitholders may be subject to taxation
in New York or in other jurisdictions and should consult their own tax
advisers in

                                      14
<PAGE>

this regard. As used herein, the term "U.S. Unitholder" means an owner of a
Unit in a Trust that (a) is (i) for United States federal income tax purposes
a citizen or resident of the United States, (ii) a corporation, partnership or
other entity created or organized in or under the laws of the United States or
of any political subdivision thereof, or (iii) an estate or trust the income
of which is subject to United States federal income taxation regardless of its
source or (b) does not qualify as a U.S. Unitholder in paragraph (a) but whose
income from a Unit is effectively connected with such Unitholder's conduct of
a United States trade or business. The term also includes certain former
citizens of the United States whose income and gain on the Units will be
taxable. Unitholders should consult their tax advisers regarding potential
foreign, state or local taxation with respect to the Units.

Retirement Plans

  Units of the Trusts may be well suited for purchase by Individual Retirement
Accounts, Keogh Plans, pension funds and other tax-deferred retirement plans.
Generally the Federal income tax relating to capital gains and income received
in each of the foregoing plans is deferred until distributions are received.
Distributions from such plans are generally treated as ordinary income but
may, in some cases, be eligible for special averaging or tax-deferred rollover
treatment. Investors considering participation in any such plan should review
specific tax laws related thereto and should consult their attorneys or tax
advisers with respect to the establishment and maintenance of any such plan.
Such plans are offered by brokerage firms and other financial institutions.
Fees and charges with respect to such plans may vary.

Trust Operating Expenses

  No annual advisory fee is charged to the Trusts by the Sponsor. The Sponsor
and/or its affiliates do, however, receive an annual fee as set forth in
"Risk/Return Summary--Fees and Expenses" in Part A of the Prospectus for
maintaining surveillance over the portfolio and for performing certain
administrative services for the Trust (the "Sponsor's Supervisory Fee"). In
providing such supervisory services, the Sponsor may purchase research from a
variety of sources, which may include dealers of the Trusts. If so provided in
Part A of the Prospectus, the Sponsor may also receive an annual fee for
providing bookkeeping and administrative services for a Trust (the
"Bookkeeping and Administrative Fee"). Such services include, but are not
limited to, the preparation of comprehensive tax statements and providing
account information to the Unitholders. If so provided in Part A of the
Prospectus, the Evaluator may also receive an annual fee for performing
evaluation services for the Trusts (the "Evaluator's Fee"). In addition, if so
provided in Part A of the Prospectus, a Trust may be charged an annual
licensing fee to cover licenses for the use of service marks, trademarks and
trade names and/or for the use of databases and research. Estimated annual
Trust expenses are as set forth in Part A of this Prospectus; if actual
expenses are higher than the estimate, the excess will be borne by the Trust.
The estimated expenses do not include the brokerage commissions and other
transactional fees payable by the Trust in purchasing and selling Securities.

  Creation and Development Fee. As set forth in Part A of the Prospectus, the
Sponsor will also receive a fee from a Trust for creating and developing the
Trust, including determining the Trust objectives, policies, composition and
size, selecting service providers and information services and for providing
other similar administrative and ministerial functions. The Trust pays this
"creation and development fee" as a percentage of the Trust's average daily
net asset value during the life of the Trust. In connection with the creation
and development fee, in no event will the Sponsor collect over the life of the
Trust more than the amount provided in Part A of the Prospectus. The Sponsor
will not use this fee to pay distribution expenses or as compensation for
sales efforts.

  The Trustee receives for ordinary recurring services an annual fee for each
Trust as set forth in "Risk/Return Summary--Fees and Expenses" appearing in
Part A of this Prospectus. The Trustee's Fee may be periodically adjusted in
response to fluctuations in short-term interest rates (reflecting the cost to
the Trustee of advancing funds to a Trust to meet scheduled distributions). In
addition, the Sponsor's

                                      15
<PAGE>

Supervisory Fee, Bookkeeping and Administrative Fee, Evaluator's Fee and the
Trustee's Fee may be adjusted in accordance with the cumulative percentage
increase of the United States Department of Labor's Consumer Price Index
entitled "All Services Less Rent of Shelter" since the establishment of the
Trusts. In addition, with respect to any fees payable to the Sponsor or an
affiliate of the Sponsor for providing bookkeeping and other administrative
services, supervisory services and evaluation services, such individual fees
may exceed the actual costs of providing such services for a Trust, but at no
time will the total amount received for such services, in the aggregate,
rendered to all unit investment trusts of which John Nuveen & Co. Incorporated
is the Sponsor in any calendar year exceed the actual cost to the Sponsor or
its affiliates of supplying such services, in the aggregate, in such year. The
Trustee has the use of funds, if any, being held in the Income and Capital
Accounts of each Trust for future distributions, payment of expenses and
redemptions. These Accounts are non-interest bearing to Unitholders. Pursuant
to normal banking procedures, the Trustee benefits from the use of funds held
therein. Part of the Trustee's compensation for its services to the Trusts is
expected to result from such use of these funds.

  The following are additional expenses of the Trusts and, when paid by or are
owed to the Trustee, are secured by a lien on the assets of the Trust or
Trusts to which such expenses are allocable: (1) the expenses and costs of any
action undertaken by the Trustee to protect the Trusts and the rights and
interests of the Unitholders; (2) all taxes and other governmental charges
upon the Securities or any part of the Trusts (no such taxes or charges are
being levied or made or, to the knowledge of the Sponsor, contemplated); (3)
amounts payable to the Trustee as fees for ordinary recurring services and for
extraordinary non-recurring services rendered pursuant to the Indenture, all
disbursements and expenses, including counsel fees (including fees of counsel
which the Trustee may retain) sustained or incurred by the Trustee in
connection therewith; and (4) any losses or liabilities accruing to the
Trustee without negligence, bad faith or willful misconduct on its part. The
expenses are paid monthly and the Trustee is empowered to sell Securities in
order to pay these amounts if funds are not otherwise available in the
applicable Income and Capital Accounts.

  Unless the Sponsor determines that an audit is not required, the Indenture
requires each Trust to be audited on an annual basis at the expense of the
Trust by independent public accountants selected by the Sponsor. The Trustee
shall not be required, however, to cause such an audit to be performed if its
cost to a Trust shall exceed $.005 per Unit on an annual basis. Unitholders of
a Trust covered by an audit may obtain a copy of the audited financial
statements upon request.

Distributions to Unitholders

  The Trustee will distribute any net income received with respect to any of
the Securities in a Trust on or about the Income Distribution Dates to
Unitholders of record on the preceding Income Record Date. See "Distributions"
in Part A of this Prospectus. Persons who purchase Units will commence
receiving distributions only after such person becomes a Record Owner.
Notification to the Trustee of the transfer of Units is the responsibility of
the purchaser, but in the normal course of business such notice is provided by
the selling broker/dealer. Proceeds received on the sale of any Securities in
a Trust, to the extent not used to meet redemptions of Units, pay the deferred
sales charge or pay expenses will be distributed on the last day of each month
if the amount available for distribution equals at least $1.00 per 100 Units
("Capital Distribution Dates") to Unitholders of record on the fifteenth day
of each applicable month ("Capital Record Dates"). The Trustee is not required
to pay interest on funds held in the Capital Account of a Trust (but may
itself earn interest thereon and therefore benefit from the use of such
funds). A Unitholder's pro rata portion of the Capital Account, less expenses,
will be distributed as part of the final liquidation distribution.

  It is anticipated that the deferred sales charge will be collected from the
Capital Account of the Trusts and that amounts in the Capital Account will be
sufficient to cover the cost of the deferred sales charge. To the extent that
amounts in the Capital Account are insufficient to satisfy the then current

                                      16
<PAGE>

deferred sales charge obligation, Securities may be sold to meet such
shortfall. Distributions of amounts necessary to pay the deferred portion of
the sales charge will be made to an account designated by the Sponsor for
purposes of satisfying a Unitholder's deferred sales charge obligations.

  Under regulations issued by the Internal Revenue Service, the Trustee is
required to withhold a specified percentage of any distribution made by a
Trust if the Trustee has not been furnished the Unitholder's tax
identification number in the manner required by such regulations. Any amount
so withheld is transmitted to the Internal Revenue Service and may be
recovered by the Unitholder under certain circumstances by contacting the
Trustee, otherwise the amount may be recoverable only when filing a tax
return. Under normal circumstances, the Trustee obtains the Unitholder's tax
identification number from the selling broker. However, a Unitholder should
examine his or her statements from the Trustee to make sure that the Trustee
has been provided a certified tax identification number in order to avoid this
possible "back-up withholding." In the event the Trustee has not been
previously provided such number, one should be provided as soon as possible.

  Within a reasonable time after a Trust is terminated, each Unitholder who is
not a Rollover Unitholder will, upon surrender of his Units for redemption,
receive (i) the pro rata share of the amounts realized upon the disposition of
Securities, unless he or she elects an In-Kind Distribution as described under
"REDEMPTION" and (ii) a pro rata share of any other assets of such Trust, less
expenses of such Trust.

  The Trustee will credit to the Income Account of a Trust any dividends
received on the Securities therein. All other receipts (e.g., return of
capital, etc.) are credited to the Capital Account of a Trust.

  The Trustee may establish reserves (the "Reserve Account") within a Trust
for state and local taxes, if any, and any governmental charges payable out of
such Trust.

  Distribution Reinvestment. Any Unitholder may elect to have each
distribution on Units, other than the final liquidating distribution in
connection with the termination of a Trust, automatically reinvested in
additional Units of such Trust without additional sales charges. If you elect
to have distributions reinvested into additional Units of your Trust, in
addition to the reinvestment Units you receive you will also be credited
additional Units with a dollar value at the time of reinvestment sufficient to
offset the amount of any remaining deferred sales charge to be collected on
such reinvestment Units. The dollar value of these additional Units (as with
all Units) will fluctuate over time. Each person who purchases Units of a
Trust may elect to participate in the reinvestment option by notifying the
Trustee in writing of their election. Reinvestment may not be available in all
states. Notification to the Trustee must be received within one year after the
Initial Date of Deposit. So long as the election is received by the Trustee at
least 10 days prior to the Record Date for a given distribution, each
subsequent distribution of income and/or capital, as selected by the
Unitholder, will be automatically applied by the Trustee to purchase
additional Units of a Trust. It should be remembered that even if
distributions are reinvested, they are still treated as distributions for
income tax purposes.

Accumulation Plan

  The Sponsor is also the principal underwriter of several open-end mutual
funds (the "Accumulation Funds") into which Unitholders may choose to reinvest
Trust distributions. Unitholders may elect to reinvest income and capital
distributions automatically, without any sales charge. Each Accumulation Fund
has investment objectives which differ in certain respects from those of the
Trusts and may invest in Securities which would not be eligible for deposit in
the Trusts. Further information concerning the Accumulation Plan and a list of
Accumulation Funds is set forth in the Information Supplement of this
Prospectus, which may be obtained by contacting the Trustee at (800) 257-8787.

  Participants may at any time, by so notifying the Trustee in writing, elect
to change the Accumulation Fund into which their distributions are being
reinvested, to change from capital only reinvestment to reinvestment of both
capital and income or vice versa, or to terminate their participation in the
Accumulation Plan altogether and receive future distributions on their Units
in cash. Such notice will be effective as of the next Record Date occurring at
least 10 days after the Trustee's receipt of the notice. There will be no
charge or other penalty for such change of election or termination. The

                                      17
<PAGE>

character of Trust distributions for income tax purposes will remain unchanged
even if they are reinvested in an Accumulation Fund.

Reports to Unitholders

  The Trustee shall furnish Unitholders of a Trust in connection with each
distribution, a statement of the amount of income, if any, and the amount of
other receipts (received since the preceding distribution) being distributed,
expressed in each case as a dollar amount representing the pro rata share of
each Unit of a Trust outstanding. Within a reasonable period of time after the
end of each calendar year, the Trustee shall furnish to each person, who at
any time during the calendar year was a registered Unitholder of a Trust, a
statement with respect to such Trust that provides (1) a summary of
transactions in the Trust for such year; (2) any Security sold during the year
and the Securities held at the end of such year by the Trust; (3) the
redemption price per Unit based upon a computation thereof on the 31st day of
December of such year (or the last business day prior thereto); and (4)
amounts of income and capital distributed during such year.

  In order to comply with Federal and state tax reporting requirements,
Unitholders will be furnished, upon request to the Trustee, evaluations of the
Securities in the Trusts.

Unit Value and Evaluation

  The value of a Trust is determined by the Trustee on the basis of (1) the
cash on hand in the Trust other than cash deposited in the Trust to purchase
Securities at the Evaluation Time not applied to the purchase of such
Securities; (2) the aggregate value of the Securities held in the Trust, as
determined by the Evaluator on the basis of the aggregate underlying value of
the Securities in the Trust next computed; (3) dividends receivable on the
Securities trading ex-dividend as of the date of computation; and (4) all
other assets of the Trust; and deducting therefrom: (1) amounts representing
any applicable taxes or governmental charges and amounts due the Sponsor or
Trustee for indemnification or extraordinary expenses payable out of such
Trust for which no deductions had been made for the purpose of additions to
the Reserve Account; (2) any amounts owing to the Trustee for its advances;
(3) an amount representing estimated accrued expenses of the Trust, including,
but not limited to, unpaid fees and expenses of the Trustee (including legal
fees) and the Sponsor; (4) amounts representing unpaid organization costs; (5)
cash held for distribution to Unitholders of record of the Trust or for
redemption of tendered Units as of the business day prior to the evaluation
being made; and (6) other liabilities incurred by the Trust. The result of
such computation is divided by the number of Units of such Trust outstanding
as of the date thereof and rounded to the nearest cent to determine the per
Unit value ("Unit Value") of such Trust. The Trustee may determine the
aggregate value of the Securities in the Trust in the following manner: if the
Securities are listed on a foreign or U.S. securities exchange or The NASDAQ
Stock Market, Inc. ("listed Securities"), this evaluation is generally based
on the most recent closing sale price prior to or on the Evaluation Time on
that exchange or that system where the Securities are principally traded (if a
listed Security is listed on the New York Stock Exchange ("NYSE") the closing
sale price on the NYSE shall apply) or, if there is no closing sale price on
that exchange or system, at the closing bid prices (ask prices for primary
market purchases). If the Securities are not so listed, the evaluation shall
generally be based on the current bid prices at the Evaluation Time (ask
prices for primary market purchases) on the over-the-counter market (unless it
is determined that these prices are inappropriate as a basis for valuation).
If current bid prices (ask prices for primary market purchases) are
unavailable, the evaluation is generally determined (a) on the basis of
current bid prices (ask prices for primary market purchases) for comparable
securities, (b) by appraising the value of the Securities on the bid side (ask
side for primary market purchases) of the market or (c) by any combination of
the above. For foreign Securities the aggregate underlying value of the
Securities during the initial offering period is computed on the basis of the
offering side value of the relevant currency exchange rate expressed in U.S.
dollars as of the Evaluation Time. After the initial offering period has
ended, the aggregate underlying value of the foreign Securities is computed on
the basis of the bid side value of the relevant currency exchange rate
expressed in U.S. dollars as of the Evaluation Time.

                                      18
<PAGE>

  With respect to any Security not listed on a foreign or U.S. securities
exchange or The NASDAQ Stock Market, Inc. or, with respect to a Security so
listed but in the unusual circumstance in which the Evaluator deems the
closing sale price on the relevant exchange to be inappropriate as a basis for
valuation, upon the Evaluator's request, the Sponsor shall, from time to time,
designate one or more evaluation services or other sources of information on
which the Evaluator shall be authorized conclusively to rely in evaluating
such Security, and the Evaluator shall have no liability for any errors in the
information so received. The cost thereof shall be an expense reimbursable to
the Trustee from the Income and Capital Accounts.

Distributions of Units to the Public

  Nuveen, in addition to being the Sponsor, is the sole Underwriter of the
Units. It is the intention of the Sponsor to qualify Units of the Trusts for
sale under the laws of substantially all of the states of the United States of
America.

  Promptly following the deposit of Securities in exchange for Units of the
Trusts, it is the practice of the Sponsor to place all of the Units as
collateral for a letter or letters of credit from one or more commercial banks
under an agreement to release such Units from time to time as needed for
distribution. Under such an arrangement the Sponsor pays such banks
compensation based on the then current interest rate. This is a normal
warehousing arrangement during the period of distribution of the Units to
public investors. To facilitate the handling of transactions, sales of Units
shall be limited to transactions involving a minimum of either $1,000 or 100
Units ($500 or nearest whole number of Units whose value is less than $500 for
IRA purchases), whichever is less. The Sponsor reserves the right to reject,
in whole or in part, any order for the purchase of Units.

  The Sponsor plans to allow a discount to brokers and dealers in connection
with the distribution of Units. The amounts of such discounts are set forth in
Part A of this Prospectus.

  The Sponsor may maintain a secondary market for Units of each Trust. See
"MARKET FOR UNITS."

  The Sponsor reserves the right to change the amount of the dealer
concessions set forth in Part A of this Prospectus from time to time.

  For Units purchased during the initial offering period by Unitholders who
utilize redemption or termination proceeds from other Nuveen-sponsored unit
investment trusts and receive the sales charge applicable for "Rollover
Purchases" as described in Part A of the Prospectus, dealers are entitled to
receive the concession applicable for "Rollover Purchases" as provided in Part
A of the Prospectus.

  Initially, for Nuveen Five-Year Sector Portfolios, Nuveen Five-Year Legacy
Portfolios and Arvest Regional ImpactTM Portfolios, the Sponsor plans to allow
a concession to selling dealers in the secondary market of 3.5% of the Public
Offering Price for non-breakpoint purchases of Units in a given transaction.
The concession paid to dealers is reduced or eliminated in connection with
Units sold in transactions to investors that receive reduced sales charges
based on the number of Units sold or in connection with Units sold in Wrap
Account Purchases and to other investors entitled to the sales charge
reduction applicable for Wrap Account Purchases as provided in "PUBLIC
OFFERING PRICE", as shown below. Commencing with the last day of the month
following the end of the deferred sales charge period, the concession will be
65% of the then current maximum sales charge at the appropriate breakpoint
level.

<TABLE>
<CAPTION>
                                                                           %
                                                                        Discount
                               Number of Units*                         per Unit
                               ----------------                         --------
        <S>                                                             <C>
        Less than 5,000................................................   3.50
        5,000 to 9,999.................................................   3.25
        10,000 to 24,999...............................................   3.00
        25,000 to 49,999...............................................   2.50
        50,000 to 99,999...............................................   1.50
        100,000 or more................................................   0.75
        Wrap Account Purchases.........................................   0.00
</TABLE>
            --------
            * Sales charge reductions are computed both on a
              dollar basis and on the basis of the number of
              Units purchased, using the equivalent of 5,000
              Units to $50,000, 10,000 Units to $100,000 etc.,
              and will be applied on that basis which is more
              favorable to you and may result in a reduction in
              the discount per Unit.


                                      19
<PAGE>

  Volume incentives can be earned as a marketing allowance by Eligible Dealer
Firms who reach cumulative firm sales or sales arrangement levels of a
specified dollar amount of the Nuveen--The Dow 5SM Portfolios and Nuveen--The
Dow 10SM Portfolios sold in the primary market from January 3, 2000 through
December 31, 2000 (the "Incentive Period"), as set forth in the table below.
Eligible Dealer Firms are dealers that are providing marketing support for
Nuveen unit trusts in the form of 1) distributing or permitting the
distribution of marketing materials and other product information, 2)
providing Nuveen representatives access to the dealer's branch offices, and 3)
generally facilitating the placement of orders by the dealer's registered
representatives such as putting Nuveen unit trusts on their order entry
screens. Eligible Dealer Firms will not include firms that solely provide
clearing services to broker/dealer firms. For firms that meet the necessary
volume level, volume incentives may be given on all trades involving the
applicable trusts originated from or by that firm during such trusts' primary
offering period.

<TABLE>
<CAPTION>
     Total dollar amount sold
      over Incentive Period                        Volume Incentive
   ----------------------------  ----------------------------------------------------
   <S>                           <C>
   $ 10,000,000 to $ 49,999,999  0.10% on sales up to $49,999,999
   $ 50,000,000 to $ 99,999,999  0.15% on sales between $50,000,000 and $99,999,999
   $100,000,000 to $199,999,999  0.20% on sales between $100,000,000 and $199,999,999
   $200,000,000 or more          0.25% on sales over $200,000,000
</TABLE>

  In addition, volume incentives can be earned as a marketing allowance by
Eligible Dealer Firms who reach cumulative firm sales or sales arrangement
levels of a specified dollar amount of Nuveen unit trusts (other than any
series of the Nuveen--The Dow 5SM Portfolios and Nuveen--The Dow 10SM
Portfolios) sold in the primary or secondary market during any quarter as set
forth in the table below. For purposes of determining the applicable volume
incentive rate for a given quarter, the dollar amount of all units sold over
the current and three previous quarters (the "Measuring Period") is
aggregated. The volume incentive received by the dealer firm will equal the
dollar amount of units sold during the current quarter times the highest
applicable rate for the Measuring Period. For firms that meet the necessary
volume level, volume incentives may be given on all applicable trades
originated from or by that firm.

<TABLE>
<CAPTION>
    Total dollar amount sold
     over Measuring Period                            Volume Incentive
   --------------------------                 --------------------------------
   <S>                                        <C>
   $ 5,000,000 to $ 9,999,999                 0.10% of current quarter sales
   $10,000,000 to $19,999,999                 0.125% of current quarter sales
   $20,000,000 to $49,999,999                 0.1375% of current quarter sales
   $50,000,000 or more                        0.15% of current quarter sales
</TABLE>

  Only sales through the Sponsor qualify for volume incentives and for meeting
minimum requirements. The Sponsor reserves the right to modify or change the
volume incentive schedule at any time and make the determination as to which
firms qualify for the marketing allowance and the amount paid.

  Firms are not entitled to receive any dealer concession or volume incentives
for any sales made to investors which qualified as Discounted Purchases (as
defined in "PUBLIC OFFERING PRICE") during the primary or secondary market.
(See "PUBLIC OFFERING PRICE.")

                                      20
<PAGE>

Ownership and Transfer of Units

  The ownership of Units is evidenced by registered Certificates unless the
Unitholder expressly requests that ownership be evidenced by a book entry
position recorded on the books and records of the Trustee. The Trustee is
authorized to treat as the owner of Units that person who at the time is
registered as such on the books of the Trustee. Any Unitholder who holds a
Certificate may change to book entry ownership by submitting to the Trustee the
Certificate along with a written request that the Units represented by such
Certificate be held in book entry form. Likewise, a Unitholder who holds Units
in book entry form may obtain a Certificate for such Units by written request
to the Trustee. Units may be held in denominations of one Unit or any multiple
or fraction thereof. Fractions of Units are computed to three decimal places.
Any Certificates issued will be numbered serially for identification, and are
issued in fully registered form, transferable only on the books of the Trustee.
Book entry Unitholders will receive a Book Entry Position Confirmation
reflecting their ownership.

  Units are transferable by making a written request to the Trustee and, in the
case of Units evidenced by Certificate(s), by presenting and surrendering such
Certificate(s) to the Trustee, The Chase Manhattan Bank, at 4 New York Plaza,
New York, NY 10004-2413, properly endorsed or accompanied by a written
instrument or instruments of transfer. The Certificate(s) should be sent
registered or certified mail for the protection of the Unitholders. Each
Unitholder must sign such written request, and such Certificate(s) or transfer
instrument, exactly as his name appears on (a) the face of the Certificate(s)
representing the Units to be transferred, or (b) the Book Entry Position
Confirmation(s) relating to the Units to be transferred. Such signature(s) must
be guaranteed by a guarantor acceptable to the Trustee. In certain instances
the Trustee may require additional documents such as, but not limited to, trust
instruments, certificates of death, appointments as executor or administrator
or certificates of corporate authority. Mutilated Certificates must be
surrendered to the Trustee in order for a replacement Certificate to be issued.
Although at the date hereof no charge is made and none is contemplated, a
Unitholder may be required to pay $2.00 to the Trustee for each Certificate
reissued or transfer of Units requested and to pay any governmental charge
which may be imposed in connection therewith.

Replacement of Lost, Stolen or Destroyed Certificates

  To obtain a new Certificate replacing one that has been lost, stolen, or
destroyed, the Unitholder must furnish the Trustee with sufficient
indemnification and pay such expenses as the Trustee may incur. This
indemnification must be in the form of an Open Penalty Bond of Indemnification.
The premium for such an indemnity bond may vary, but currently amounts to 1% of
the market value of the Units represented by the Certificate. In the case
however, of a Trust as to which notice of termination has been given, the
premium currently amounts to 0.5% of the market value of the Units represented
by such Certificate.

Redemption

  Unitholders may redeem all or a portion of their Units by (1) making a
written request for such redemption (book entry Unitholders may use the
redemption form on the reverse side of their Book Entry Position Confirmation)
to the Trustee at 4 New York Plaza, New York NY 10004-2413 (redemptions of
1,000 Units or more will require a signature guarantee), (2) in the case of
Units evidenced by a Certificate, by also tendering such Certificate to the
Trustee, duly endorsed or accompanied by proper instruments of transfer with
signatures guaranteed as explained above, or provide satisfactory indemnity
required in connection with lost, stolen or destroyed Certificates and (3)
payment of applicable governmental charges, if any. Certificates should be sent
only by registered or certified mail to minimize the possibility of their being
lost or stolen. (See "OWNERSHIP AND TRANSFER OF UNITS.") No redemption fee will
be charged. A Unitholder may authorize the Trustee to honor telephone
instructions for the redemption of Units held in book entry form. Units
represented by Certificates may not be redeemed by telephone. The proceeds of
Units redeemed by telephone will be

                                       21
<PAGE>

sent by check either to the Unitholder at the address specified on his account
or to a financial institution specified by the Unitholder for credit to the
account of the Unitholder. A Unitholder wishing to use this method of
redemption must complete a Telephone Redemption Authorization Form and furnish
the Form to the Trustee. Telephone Redemption Authorization Forms can be
obtained from a Unitholder's registered representative or by calling the
Trustee. Once the completed Form is on file, the Trustee will honor telephone
redemption requests by any authorized person. The time a telephone redemption
request is received determines the "date of tender" as discussed below. The
redemption proceeds will be mailed within three business days following the
telephone redemption request. Only Units held in the name of individuals may
be redeemed by telephone; accounts registered in broker name, or accounts of
corporations or fiduciaries (including among others, trustees, guardians,
executors and administrators) may not use the telephone redemption privilege.

  On the third business day following the date of tender, the Unitholder will
be entitled to receive in cash for each Unit tendered an amount equal to the
Unit Value of such Trust determined by the Trustee, as of 4:00 p.m. eastern
time, or as of any earlier closing time on a day on which the Exchange is
scheduled in advance to close at such earlier time, on the date of tender as
defined hereafter ("Redemption Price"). During the period ending with the
earlier of six months after the Initial Date of Deposit or the end of the
initial offering period, the Redemption Price per Unit includes estimated
organization costs per Unit. After such period, the Redemption Price will not
include such estimated organization costs. See "Risk/Return Summary--Fees and
Expenses" in Part A of the Prospectus. The price received upon redemption may
be more or less than the amount paid by the Unitholder depending on the value
of the Securities on the date of tender. Units subject to a deferred sales
charge which are tendered for redemption prior to such time as the entire
deferred sales charge on such Units has been collected will be assessed the
amount of the remaining deferred sales charge at the time of redemption. In
addition, in the event of the death of a Unitholder within the one-year period
prior to redemption, any deferred sales charge remaining at the time of
redemption shall be waived. Unitholders should check with the Trustee or their
broker to determine the Redemption Price before tendering Units.

  The "date of tender" is deemed to be the date on which the request for
redemption of Units is received in proper form by the Trustee, except that a
redemption request received after 4:00 p.m. eastern time, or as of any earlier
closing time on a day on which the Exchange is scheduled in advance to close
at such earlier time, or on any day on which the Exchange is normally closed,
the date of tender is the next day on which such Exchange is normally open for
trading and such request will be deemed to have been made on such day and the
redemption will be effected at the Redemption Price computed on that day.

  If so provided in Part A of the Prospectus, any Unitholder tendering at
least 1,000 Units of a Trust for redemption or whose Units are worth $10,000
may request by written notice submitted at the time of tender from the
Trustee, in lieu of a cash redemption, a distribution of shares of Securities
in an amount and value of Securities per Unit equal to the Redemption Price
Per Unit, as determined as of the evaluation next following tender. In-kind
distributions ("In-Kind Distributions") shall be made by the Trustee through
the distribution of each of the Securities in book-entry form to the account
of the Unitholder's bank or broker/dealer at the Depository Trust Company. An
In-Kind Distribution will be reduced by customary transfer and registration
charges. The tendering Unitholder will receive his pro rata number of whole
shares of each of the Securities comprising a portfolio and cash from the
Capital Account equal to the fractional shares to which the tendering
Unitholder is entitled. The Trustee may adjust the number of shares of any
issue of Securities included in a Unitholder's In-Kind Distribution to
facilitate the distribution of whole shares, such adjustment to be made on the
basis of the value of Securities on the date of tender. If funds in the
Capital Account are insufficient to cover the required cash distribution to
the tendering Unitholder, the Trustee may sell Securities in the manner
described below.

                                      22
<PAGE>

  Under regulations issued by the Internal Revenue Service, the Trustee may be
required to withhold a specified percentage of the principal amount of a Unit
redemption if the Trustee has not been furnished the redeeming Unitholder's
tax identification number in the manner required by such regulations. For
further information regarding this withholding, see "DISTRIBUTIONS TO
UNITHOLDERS." In the event the Trustee has not been previously provided such
number, one must be provided at the time redemption is requested.

  Any amounts paid on redemption representing income shall be withdrawn from
the Income Account of a Trust to the extent that funds are available for such
purpose, or from the Capital Account. All other amounts paid on redemption
shall be withdrawn from the Capital Account.

  The Trustee is empowered to sell Securities of the Trust in order to make
funds available for redemption. To the extent that Securities are sold, the
size and diversity of the Trust will be reduced. Such sales may be required at
a time when Securities would not otherwise be sold and might result in lower
prices than might otherwise be realized.

  The Redemption Price per Unit during the secondary market will be determined
on the basis of the Unit Value of the Trust as of the Evaluation Time. After
the period ending with the earlier of six months after the Initial Date of
Deposit or the end of the initial offering period, the Redemption Price will
not include estimated organization costs. See "Risk/Return Summary--Fees and
Expenses" in Part A of the Prospectus. See "UNIT VALUE AND EVALUATION" for a
more detailed discussion of the factors included in determining Unit Value.
The Redemption Price per Unit will be assessed the amount, if any, of the
remaining deferred sales charge at the time of redemption.

  The right of redemption may be suspended and payment postponed for any
period during which the New York Stock Exchange is closed, other than for
customary weekend and holiday closings, or during which the Securities and
Exchange Commission determines that trading on the New York Stock Exchange is
restricted or any emergency exists, as a result of which disposal or
evaluation of the Securities is not reasonably practicable, or for such other
periods as the Securities and Exchange Commission may by order permit. Under
certain extreme circumstances, the Sponsor may apply to the Securities and
Exchange Commission for an order permitting a full or partial suspension of
the right of Unitholders to redeem their Units. The Trustee is not liable to
any person in any way for any loss or damage which may result from any such
suspension or postponement.

Special Redemption, Liquidation and Investment in a New Trust

  If so provided in Part A of the Prospectus for applicable Strategy Trusts,
it is expected that a special redemption and liquidation will be made of all
Units of a Trust held by any Unitholder (a "Rollover Unitholder") who
affirmatively notifies the Trustee in writing by the appropriate Rollover
Notification Date specified in "Rollover Trusts" in Part A of this Prospectus
that he or she desires to participate as a Rollover Unitholder.

  All Units of Rollover Unitholders will be redeemed In-Kind during the
appropriate Special Redemption and Liquidation Period as determined by the
Sponsor and the underlying Securities will be distributed to the Distribution
Agent (currently the Trustee) on behalf of the Rollover Unitholders. During
the Special Redemption and Liquidation Period (as set forth in "Rollover
Trusts" in Part A of the Prospectus), the Distribution Agent will be required
to sell all of the underlying Securities on behalf of Rollover Unitholders.
The sales proceeds will be net of brokerage fees, governmental charges or any
expenses involved in the sales.

                                      23
<PAGE>

  The Distribution Agent may engage the Sponsor, as its agent, or other brokers
to sell the distributed Securities. The Securities will be sold as quickly as
is practicable during the appropriate Special Redemption and Liquidation
Period. The Sponsor does not anticipate that the period will be longer than one
or two days, given that the Securities are usually highly liquid. The liquidity
of any Security depends on the daily trading volume of the Security and the
amount that the Sponsor has available for sale on any particular day.

  The Rollover Unitholders' proceeds will be invested in a New Trust or a trust
with a similar investment strategy (as selected by the Unitholder), if then
registered and being offered. The proceeds of redemption will be used to buy
New Trust units as the proceeds become available. Any Rollover Unitholder may
thus be redeemed out of a Trust and become a holder of an entirely different
trust, a New Trust, with a different portfolio of Securities. In accordance
with the Rollover Unitholders' offer to purchase the New Trust units, the
proceeds of the sales (and any other cash distributed upon redemption) are
expected to be invested in a New Trust, at the public offering price, including
the applicable sales charge per Unit specified in Part A of that trust's
Prospectus.

  The Sponsor intends to create the New Trust units as quickly as possible,
depending upon the availability and reasonably favorable prices of the
Securities included in a New Trust portfolio, and it is intended that Rollover
Unitholders will be given first priority to purchase the New Trust units. The
Sponsor may also permit Rollover Unitholders to elect to have their proceeds
invested in a trust with a similar investment strategy, if such trust is then
registered in the Unitholder's state of residence and being offered. There can
be no assurance, however, as to the exact timing of the creation of the New
Trust units or the aggregate number of New Trust units which the Sponsor will
create. The Sponsor may, in its sole discretion, stop creating new units
(whether permanently or temporarily) at any time it chooses, regardless of
whether all proceeds of the Special Redemption and Liquidation have been
invested on behalf of Rollover Unitholders. Cash which has not been invested on
behalf of the Rollover Unitholders in New Trust units will be distributed
within a reasonable time after such occurrence. However, since the Sponsor can
create units, the Sponsor anticipates that sufficient units can be created,
although moneys in a New Trust may not be fully invested on the next business
day.

  The process of redemption, liquidation, and investment in a New Trust is
intended to allow for the fact that the portfolios selected by the Sponsor are
chosen on the basis of growth potential only for the life of the Trust, at
which point a new portfolio is chosen. A similar process of redemption,
liquidation and investment in a New Trust may be available prior to the
Mandatory Termination Date of the Trust.

  It should also be noted that Rollover Unitholders may realize taxable capital
gains on the Special Redemption and Liquidation but, in certain circumstances,
will not be entitled to a deduction for certain capital losses and, due to the
procedures for investing in a New Trust, no cash would be distributed at that
time to pay any taxes. Included in the cash for the Special Redemption and
Liquidation may be an amount of cash attributable to a Unitholder's final
distribution of dividend income; accordingly, Rollover Unitholders also will
not have cash from this source distributed to pay any taxes. (See "TAX
STATUS.") Recently, legislation has been enacted that reduces the maximum
stated marginal tax rate for certain capital gains for investments held for
more than 1 year to 20% (10% in the case of certain taxpayers in the lowest tax
bracket). Potential investors should consult their tax advisors regarding the
potential effect of the Act on their investment in Units. In addition, it
should be noted that legislative proposals are introduced from time to time
that affect tax rates and could affect relative differences at which ordinary
income and capital gains are taxed.

  In addition, during this period a Unitholder will be at risk to the extent
that Securities are not sold and will not have the benefit of any stock
appreciation to the extent that moneys have not been

                                       24
<PAGE>

invested; for this reason, the Sponsor will be inclined to sell and purchase
the Securities in as short a period as it can without materially adversely
affecting the price of the Securities.

  Unitholders who do not inform the Distribution Agent that they wish to have
their Units so redeemed and liquidated ("Remaining Unitholders") will not
realize capital gains or losses due to the Special Redemption and Liquidation,
and will not be charged any additional sales charge.

  The Sponsor may for any reason, in its sole discretion, decide not to
sponsor the New Trusts or any subsequent series of the Trusts, without penalty
or incurring liability to any Unitholder. If the Sponsor so decides, the
Sponsor shall notify the Unitholders before the appropriate Special Redemption
and Liquidation Period. All Unitholders will then be remaining Unitholders,
with rights to ordinary redemption as before. (See "REDEMPTION.") The Sponsor
may modify the terms of the New Trusts or any subsequent series of the Trusts.
The Sponsor may also modify, suspend or terminate the Rollover Option or any
exchange option without notice except in certain limited circumstances.
However, generally, the termination of the Rollover Option or an exchange
option or a material amendment to such options requires notice of at least 60
days prior to the effective date of such termination or amendment.

Purchase of Units by the Sponsor

  The Trustee will notify the Sponsor of any tender of Units for redemption.
If the Sponsor's bid in the secondary market at that time equals or exceeds
the Redemption Price it may purchase such Units by notifying the Trustee
before the close of business on the second succeeding business day and by
making payment therefor to the Unitholder not later than the day on which
payment would otherwise have been made by the Trustee. (See "REDEMPTION.") The
Sponsor's current practice is to bid at the Redemption Price in the secondary
market. Units held by the Sponsor may be tendered to the Trustee for
redemption as any other Units.

Removal of Securities from the Trusts

  The portfolios of the Trusts are not "managed" by the Sponsor or the
Trustee; their activities described herein are governed solely by the
provisions of the Indenture. The Indenture provides that the Sponsor may (but
need not) direct the Trustee to dispose of a Security in the following
circumstances: (1) the issuer defaults in the payment of a dividend that has
been declared and is due and payable; (2) any action or proceeding has been
instituted restraining the payment of dividends or there exists any legal
question or impediment affecting such Security; (3) the issuer of the Security
has breached a covenant or warranty which would affect the payments of
dividends, the credit standing of the issuer or otherwise impair the sound
investment character of the Security; (4) the issuer has defaulted on the
payment on any other of its outstanding obligations; (5) the price of the
Security declined to such an extent or other such credit factors exist so that
in the opinion of the Sponsor, the retention of such Securities would be
detrimental to a Trust; (6) all Securities in the Trust will be sold pursuant
to the Trust's termination; (7) the sale of Securities is required when Units
are tendered for redemption; (8) the sale of Securities is necessary to
maintain the Trust as a "regulated investment company" if the Trust has made
such election; (9) there has been a public tender offer made to a Security or
a merger or acquisition is announced affecting a Security, and that in the
Sponsor's opinion the sale or tender of the Security is in the best interest
of Unitholders; or (10) for such other reasons provided in the Prospectus or
the Indenture. Except as stated in this Prospectus, the acquisition by a Trust
of any securities or other property other than the Securities is prohibited.
Pursuant to the Indenture and with limited exceptions, the Trustee may sell
any securities or other property acquired in exchange for Securities such as
those acquired in connection with a merger or other transaction. If offered
such new or exchanged securities or properties, the Trustee shall reject the
offer. However, in the event such securities or property are nonetheless
acquired by a Trust, they may be accepted for deposit in a Trust and either
sold by the Trustee or held in a Trust pursuant to the direction of the
Sponsor. Proceeds from the sale of Securities by the Trustee are credited to
the Capital Account of a Trust for distribution to Unitholders or to meet
redemptions.

                                      25
<PAGE>

  The Trustee may also sell Securities designated by the Sponsor, or if not so
directed, in its own discretion, for the purpose of redeeming Units of a Trust
tendered for redemption and the payment of expenses.

  The Sponsor, in designating Securities to be sold by the Trustee, will
generally make selections in order to maintain, to the extent practicable, the
proportionate relationship among the number of shares of individual issues of
Securities. To the extent this is not practicable, the composition and
diversity of the Securities may be altered. In order to obtain the best price
for a Trust, it may be necessary for the Sponsor to specify minimum amounts
(generally 100 shares) in which blocks of Securities are to be sold. The
Sponsor may consider sales of Units of unit investment trusts which it sponsors
in making recommendations to the Trustee as to the selection of broker/dealers
to execute a Trust's portfolio transactions.

Information about the Trustee

  The Trustee is The Chase Manhattan Bank. Its address is 4 New York Plaza, New
York, NY 10004-2413. The Trustee is subject to supervision and examination by
the Federal Deposit Insurance Corporation, the Board of Governors of the
Federal Reserve System and either the Comptroller of the Currency or state
banking authorities.

Limitations on Liabilities of Sponsor and Trustee

  The Sponsor and the Trustee shall be under no liability to Unitholders for
taking any action or for refraining from any action in good faith pursuant to
the Indenture, or for errors in judgment, but shall be liable only for their
own negligence, lack of good faith or willful misconduct. The Trustee shall not
be liable for depreciation or loss incurred by reason of the sale by the
Trustee of any of the Securities. In the event of the failure of the Sponsor to
act under the Indenture, the Trustee may act thereunder and shall not be liable
for any action taken by it in good faith under the Indenture.

  The Trustee shall not be liable for any taxes or other governmental charges
imposed upon or in respect of the Securities or upon the interest thereon or
upon it as Trustee under the Indenture or upon or in respect of any Trust which
the Trustee may be required to pay under any present or future law of the
United States of America or of any other taxing authority having jurisdiction.
In addition, the Indenture contains other customary provisions limiting the
liability of the Trustee.

Successor Trustees and Sponsors

  The Trustee or any successor trustee may resign by executing an instrument of
resignation in writing and filing same with the Sponsor and mailing a copy of a
notice of resignation to all Unitholders then of record. Upon receiving such
notice, the Sponsor is required to promptly appoint a successor trustee. If the
Trustee becomes incapable of acting or is adjudged a bankrupt or insolvent, or
a receiver or other public officer shall take charge of its property or
affairs, the Sponsor may remove the Trustee and appoint a successor by written
instrument. The resignation or removal of a trustee and the appointment of a
successor trustee shall become effective only when the successor trustee
accepts its appointment as such. Any successor trustee shall be a corporation
authorized to exercise corporate trust powers, having capital, surplus and
undivided profits of not less than $5,000,000. Any corporation into which a
trustee may be merged or with which it may be consolidated, or any corporation
resulting from any merger or consolidation to which a trustee shall be a party,
shall be the successor trustee.

  If upon resignation of a trustee no successor has been appointed and has
accepted the appointment within 30 days after notification, the retiring
trustee may apply to a court of competent jurisdiction for the appointment of a
successor.

  If the Sponsor fails to undertake any of its duties under the Indenture, and
no express provision is made for action by the Trustee in such event, the
Trustee may, in addition to its other powers under the Indenture (1) appoint a
successor sponsor or (2) terminate the Indenture and liquidate the Trusts.


                                       26
<PAGE>

Information about the Sponsor

  Since our founding in 1898, Nuveen has been synonymous with investments that
withstand the test of time. Today, we offer a broad range of investments
designed for investors seeking to build and sustain their wealth. More than 1.5
million investors have entrusted Nuveen to help them maintain the lifestyle
they currently enjoy.

  To meet the unique circumstances and financial planning needs of our
investors, Nuveen offers a wide array of taxable and tax-free investment
products--including equity and fixed-income mutual funds, defined portfolios,
exchange-traded funds, customized asset management services and cash management
products.

  Nuveen is a subsidiary of The John Nuveen Company which, in turn, is
approximately 78% owned by the St. Paul Companies, Inc. ("St. Paul"). St. Paul
is located in St. Paul, Minnesota and is principally engaged in providing
property-liability insurance through subsidiaries. Nuveen is a member of the
National Association of Securities Dealers, Inc. and the Securities Industry
Association and has its principal offices located in Chicago (333 West Wacker
Drive). Nuveen maintains six regional offices.

  To help advisors and investors better understand and more efficiently use an
investment in the Trusts to reach their investment goals, the Sponsor may
advertise and create specific investment programs and systems. For example,
such activities may include presenting information on how to use an investment
in the Trust, alone or in combination with an investment in other mutual funds
or unit investment trusts sponsored by Nuveen, to accumulate assets for future
education needs or periodic payments such as insurance premiums. The Sponsor
may produce software or additional sales literature to promote the advantages
of using the Trusts to meet these and other specific investor needs.

  In advertising and sales literature, the Sponsor may provide or compare the
performance of a given investment strategy, collection of Trusts or a Trust
sponsored by the Sponsor with that of, or reflect the performance of: (1) the
Consumer Price Index; (2) equity unit trusts of the Sponsor or other unit trust
providers; (3) equity mutual funds or mutual fund indices as reported by
various independent services which monitor the performance of mutual funds, or
other industry or financial publications such as Barron's, Changing Times,
Forbes and Money Magazine; and/or (4) the S&P 500 Index or other unmanaged
indices and investment strategies. Advertisements involving these indices,
investments or strategies may reflect performance over different periods of
time by means of aggregate, average, year-by-year, or other types of total
return and performance figures. Any given performance quotation or performance
comparison should not be considered as representative of the performance of the
Trusts for any future period. Such advertising may also reflect the standard
deviation or beta of the index, investment or strategy returns for any period.
The calculation of standard deviation is sometimes referred to as the "Sharpe
measure" of return.

Information about the Evaluator

  The Trustee will serve as Evaluator of the Trusts. For the Sector Trusts, the
Sponsor intends to replace the Trustee as Evaluator during the life of the
Trusts.

  The Evaluator may resign or may be removed by the Sponsor or the Trustee, in
which event the Sponsor and the Trustee are to use their best efforts to
appoint a satisfactory successor. Such resignation or removal shall become
effective upon the acceptance of appointment by the successor Evaluator. If

                                       27
<PAGE>

upon resignation of the Evaluator no successor has accepted appointment within
30 days after notice of resignation, the Evaluator may apply to a court of
competent jurisdiction for the appointment of a successor.

  The Trustee, Sponsor and Unitholders may rely on any evaluation furnished by
the Evaluator and shall have no responsibility for the accuracy thereof.
Determinations by the Evaluator under the Indenture shall be made in good faith
upon the basis of the best information available to it, provided, however, that
the Evaluator shall be under no liability to the Trustee, Sponsor or
Unitholders for errors in judgment. This provision shall not protect the
Evaluator in any case of willful misfeasance, bad faith, gross negligence or
reckless disregard of its obligations and duties.

FORTUNE License Agreement

  The Nuveen-FORTUNE America's Most Admired Companies Portfolio (the "Product")
is not sponsored, endorsed, sold or promoted by FORTUNE Magazine ("Fortune").
Fortune makes no representation or warranty, express or implied, to the owners
of the Product or any member of the public regarding the advisability of
investing in securities generally or in the Product particularly. Fortune's
only relationship to the Licensee is the licensing of certain trademarks and
trade names of Fortune and the America's Most Admired Companies list. This list
is determined and composed by Fortune without regard to the Licensee or the
Product. Fortune has no obligation to take the needs of the Licensee or the
owners of the Product into consideration in determining, composing or
calculating the Fortune Most Admired Companies list. Fortune is not responsible
for and has not participated in the determination of the prices and amount of
the Product or the timing of the issuance or sale of the Product or in the
determination or calculation of the equation by which the Product is to be
converted into cash. Fortune has no obligation or liability in connection with
the administration, marketing or trading of the Product.

  FORTUNE MAKES NO WARRANTY, EXPRESS OR IMPLIED, AS TO RESULTS TO BE OBTAINED
BY LICENSEE, OWNERS OF THE PRODUCT, OR ANY OTHER PERSON OR ENTITY FROM THE USE
OF THE AMERICA'S MOST ADMIRED COMPANIES LIST. FORTUNE MAKES NO EXPRESS OR
IMPLIED WARRANTIES, AND EXPRESSLY DISCLAIMS ALL WARRANTIES OF MERCHANTABILITY
OR FITNESS FOR A PARTICULAR PURPOSE OR USE WITH RESPECT TO THE AMERICA'S MOST
ADMIRED COMPANIES LIST. WITHOUT LIMITING ANY OF THE FOREGOING, IN NO EVENT
SHALL FORTUNE HAVE ANY LIABILITY FOR ANY SPECIAL, PUNITIVE, INDIRECT, OR
CONSEQUENTIAL DAMAGES (INCLUDING LOST PROFITS), EVEN IF NOTIFIED OF THE
POSSIBILITY OF SUCH DAMAGES.

Other Information

Amendment of Indenture

  The Indenture may be amended by the Trustee and the Sponsor without the
consent of any of the Unitholders (1) to cure any ambiguity or to correct or
supplement any provision thereof which may be defective or inconsistent, or (2)
to make such other provisions as shall not adversely affect the Unitholders,
provided, however, that the Indenture may not be amended, without the consent
of 100% of the Unitholders, to permit the deposit or acquisition of securities
either in addition to, or in substitution for any of the Securities initially
deposited in any Trust except as stated in "COMPOSITION OF TRUSTS" regarding
the creation of additional Units and the limited right of substitution of
Replacement Securities, except for the substitution of refunding securities
under certain circumstances or except as otherwise provided in this Prospectus.
The Trustee shall advise the Unitholders of any amendment requiring the consent
of Unitholders, or upon request of the Sponsor, promptly after execution
thereof.


                                       28
<PAGE>

Termination of Indenture

  The Trust may be liquidated at any time by an instrument executed by the
Sponsor and consented to by 66 2/3% of the Units of the Trust then outstanding.
The Trust may also be liquidated by the Trustee when the value of such Trust,
as shown by any evaluation, is less than 20% of the total value of the
Securities deposited in the Trust as of the conclusion of the primary offering
period and may be liquidated by the Trustee in the event that Units not yet
sold aggregating more than 60% of the Units originally created are tendered for
redemption by the Sponsor. The sale of Securities from the Trust upon
termination may result in realization of a lesser amount than might otherwise
be realized if such sale were not required at such time. For this reason, among
others, the amount realized by a Unitholder upon termination may be less than
the amount of Securities originally represented by the Units held by such
Unitholder. The Indenture will terminate upon the redemption, sale or other
disposition of the last Security held thereunder, but in no event shall it
continue beyond the Mandatory Termination Date set forth under "General
Information--Termination" in Part A of this Prospectus.

  Commencing on the Mandatory Termination Date, Securities will begin to be
sold in connection with the termination of a Trust. The Sponsor will determine
the manner, timing and execution of the sale of the Securities. Written notice
of the termination of a Trust specifying the time or times at which Unitholders
may surrender their certificates for cancellation shall be given by the Trustee
to each Unitholder at his address appearing on the registration books of such
Trust maintained by the Trustee. Unitholders not electing a distribution of
shares of Securities and who do not elect the Rollover Option (if applicable)
will receive a cash distribution from the sale of the remaining Securities
within a reasonable time after the Trust is terminated. Regardless of the
distribution involved, the Trustee will deduct from the funds of a Trust any
accrued costs, expenses, advances or indemnities provided by the Indenture,
including estimated compensation of the Trustee and costs of liquidation and
any amounts required as a reserve to provide for payment of any applicable
taxes or other governmental charges. Trustee will then distribute to each
Unitholder his pro rata share of the balance of the Income and Capital
Accounts.

Legal Opinion

  The legality of the Units offered hereby has been passed upon by Chapman and
Cutler, 111 West Monroe Street, Chicago, Illinois 60603. Carter, Ledyard &
Milburn, 2 Wall Street, New York, New York 10005, has acted as counsel for the
Trustee with respect to the Series.

Auditors

  The "Statement of Condition" and "Schedule of Investments" at the Initial
Date of Deposit included in Part A of this Prospectus have been audited by
Arthur Andersen LLP, independent public accountants, as indicated in their
report in Part A of this Prospectus, and are included herein in reliance upon
the authority of said firm as experts in giving said report.

Code of Ethics

The Sponsor and the Trusts have adopted a code of ethics requiring the
Sponsor's employees who have access to information on Trust transactions to
report personal securities transactions. The purpose of the code is to avoid
potential conflicts of interest and to prevent fraud, deception or misconduct
with respect to the Trusts.

Supplemental Information

  Upon written or telephonic request to the Trustee, investors will receive at
no cost to the investor supplemental information about this Trust, which has
been filed with the Securities and Exchange Commission and is intended to
supplement information contained in Part A and Part B of this Prospectus. This
supplement includes additional general information about the Sponsor and the
Trusts.

                                       29
<PAGE>


[LOGO NUVEEN DEFINED PORTFOLIOS]
                            NUVEEN EQUITY PORTFOLIO
                              PROSPECTUS -- PART B

                               May 15, 2000

                              Sponsor       John Nuveen & Co. Incorporated
                                            333 West Wacker Drive
                                            Chicago, IL 60606-1286
                                            Telephone: 312-917-7700


                              Trustee       The Chase Manhattan Bank
                                            4 New York Plaza
                                            New York, NY 10004-2413
                                            Telephone: 800-257-8787


             Legal Counsel to Sponsor       Chapman and Cutler
                                            111 West Monroe Street
                                            Chicago, IL 60603


                          Independent       Arthur Andersen LLP
                   Public Accountants       33 West Monroe Street
                       for the Trusts       Chicago, IL 60603

  This Prospectus does not contain complete information about the Nuveen Unit
Trusts filed with the Securities and Exchange Commission in Washington, DC
under the Securities Act of 1933 and the Investment Company Act of 1940.

  More information about the Trusts, including the code of ethics adopted by
the Sponsor and the Nuveen Unit Trusts, can be found in the Commission's Public
Reference Room. Information about the operation of the Public Reference Room
may be obtained by calling the Commission at 1-202-942-8090. Trust information
is also available on the EDGAR Database on the Commission's website at
http://www.sec.gov, or may be obtained at proscribed rates by sending an e-mail
request to [email protected] or by writing to the Commission's Public
Reference Section at 450 Fifth Street NW, Washington, D.C. 20549-0102.

  No person is authorized to give any information or representation about a
Trust not contained in Parts A or B of this Prospectus or the Information
Supplement, and you should not rely on any other information.

  When Units of a Trust are no longer available or for investors who will
reinvest into subsequent series of a Trust, this Prospectus may be used as a
preliminary Prospectus for a future series. If this is the case, investors
should note the following:

    1. Information in this Prospectus is not complete and may be changed;

    2. We may not sell these securities until the registration statement
  filed with the Securities and Exchange Commission is effective; and

    3. This Prospectus is not an offer to sell the securities of a future
  series and is not soliciting an offer to buy such securities in any state
  where the offer or sale is not permitted.

<PAGE>

                              NUVEEN UNIT TRUSTS

 NUVEEN--STANDARD & POOR'S QUALITY BUYBACK PORTFOLIO, MAY 2000 PROSPECTUS

                                 May 15, 2000
                              NUVEEN UNIT TRUSTS
                            INFORMATION SUPPLEMENT


                         NUVEEN UNIT TRUSTS, SERIES 91

     The Information Supplement provides additional information concerning the
structure and operations of a Nuveen Unit Trust not found in the prospectuses
for the Trusts. This Information Supplement is not a prospectus and does not
include all of the information that a prospective investor should consider
before investing in a Trust. This Information Supplement should be read in
conjunction with the prospectus for the Trust in which an investor is
considering investing ("PROSPECTUS"). Copies of the Prospectus can be obtained
by calling or writing the Trustee at The Chase Manhattan Bank, 4 New York Plaza,
New York, New York 10004-2413 (800) 257-8787. This Information Supplement has
been created to supplement information contained in the Prospectus.


     This Information Supplement is dated May 15, 2000. Capitalized terms have
been defined in the Prospectus.

                               TABLE OF CONTENTS

<TABLE>
<S>                                                                      <C>
ACCUMULATION PLAN.....................................................    2
INFORMATION ABOUT THE SPONSOR.........................................    4
RISK FACTORS..........................................................    5
</TABLE>

APPENDIX A--STANDARD & POOR'S EARNINGS AND DIVIDEND ratings FOR COMMON STOCKS

APPENDIX B--STANDARD & POOR'S CORPORATE RATINGS CRITERIA


                                      S-1
<PAGE>

ACCUMULATION PLAN

     The Sponsor, John Nuveen & Co. Incorporated, is also the principal
underwriter of the Accumulation Funds listed in the following table. Each of
these funds is an open-end, diversified management investment company into which
Unitholders may choose to reinvest Trust distributions automatically, without
any sales charge. Unitholders may reinvest both interest and capital
distributions or capital distributions only. Each Accumulation Fund has
investment objectives which differ in certain respects from those of the Trusts
and may invest in securities which would not be eligible for deposit in the
Trusts. The investment adviser to each Accumulation Fund is a wholly-owned
subsidiary of the Sponsor. Unitholders should contact their financial adviser or
the Sponsor to determine which of the Accumulation Funds they may reinvest into,
as reinvestment in certain of the Accumulation Funds may be restricted to
residents of a particular state or states. Unitholders may obtain a prospectus
for each Accumulation Fund through their financial adviser or through the
Sponsor at (800) 257-8787. For a more detailed description, unitholders should
read the prospectus of the Accumulation Fund in which they are interested.

     The following is a complete list of the Accumulation Funds currently
available, as of the Date of Deposit of this Prospectus, to Unitholders under
the Accumulation Plan. The list of available Accumulation Funds is subject to
change without the consent of any of the Unitholders.

ACCUMULATION FUNDS

MUTUAL FUNDS

NUVEEN FLAGSHIP MUNICIPAL TRUST
     Nuveen Municipal Bond Fund
     Nuveen Insured Municipal Bond Fund
     Nuveen Flagship All-American Municipal Bond Fund
     Nuveen Flagship Limited Term Municipal Bond Fund
     Nuveen Flagship Intermediate Municipal Bond Fund

NUVEEN FLAGSHIP MULTISTATE TRUST I
     Nuveen Flagship Arizona Municipal Bond Fund
     Nuveen Flagship Colorado Municipal Bond Fund
     Nuveen Flagship Florida Municipal Bond Fund
     Nuveen Flagship Florida Intermediate Municipal Bond Fund
     Nuveen Maryland Municipal Bond Fund
     Nuveen Flagship New Mexico Municipal Bond Fund
     Nuveen Flagship Pennsylvania Municipal Bond Fund
     Nuveen Flagship Virginia Municipal Bond Fund

NUVEEN FLAGSHIP MULTISTATE TRUST II
     Nuveen California Municipal Bond Fund
     Nuveen California Insured Municipal Bond Fund
     Nuveen Flagship Connecticut Municipal Bond Fund
     Nuveen Massachusetts Municipal Bond Fund
     Nuveen Massachusetts Insured Municipal Bond Fund
     Nuveen Flagship New Jersey Municipal Bond Fund
     Nuveen Flagship New Jersey Intermediate Municipal Bond Fund
     Nuveen Flagship New York Municipal Bond Fund
     Nuveen New York Insured Municipal Bond Fund

                                      S-2

<PAGE>

NUVEEN FLAGSHIP MULTISTATE TRUST III
     Nuveen Flagship Alabama Municipal Bond Fund
     Nuveen Flagship Georgia Municipal Bond Fund
     Nuveen Flagship Louisiana Municipal Bond Fund
     Nuveen Flagship North Carolina Municipal Bond Fund
     Nuveen Flagship South Carolina Municipal Bond Fund
     Nuveen Flagship Tennessee Municipal Bond Fund

NUVEEN FLAGSHIP MULTISTATE TRUST IV
     Nuveen Flagship Kansas Municipal Bond Fund
     Nuveen Flagship Kentucky Municipal Bond Fund
     Nuveen Flagship Kentucky Limited Term Municipal Bond Fund
     Nuveen Flagship Michigan Municipal Bond Fund
     Nuveen Flagship Missouri Municipal Bond Fund
     Nuveen Flagship Ohio Municipal Bond Fund
     Nuveen Flagship Wisconsin Municipal Bond Fund

Flagship Utility Income Fund


Nuveen Municipal Money Market Fund, Inc.

Nuveen Taxable Funds, Inc.

Nuveen Dividend and Growth Fund

NUVEEN INVESTMENT TRUST
     Nuveen Growth and Income Stock Fund
     Nuveen Balanced Stock and Bond Fund
     Nuveen Balanced Municipal and Stock Fund
     Nuveen European Value Fund

NUVEEN INVESTMENT TRUST II
     Nuveen Rittenhouse Growth Fund
     Nuveen Innovation Fund
     Nuveen International Growth Fund

NUVEEN INVESTMENT TRUST III

     Nuveen Income Fund

MONEY MARKET FUNDS
     Nuveen California Tax-Free Money Market Fund
     Nuveen Massachusetts Tax-Free Money Market Fund
     Nuveen New York Tax-Free Money Market Fund
     Nuveen Tax-Free Reserves, Inc.
     Nuveen Tax-Exempt Money Market Fund, Inc.

     Each person who purchases Units of a Trust may become a participant in the
Accumulation Plan and elect to have his or her distributions on Units of the
Trust invested directly in shares of one of the Accumulation Funds. Reinvesting
Unitholders may select any interest distribution plan. Thereafter, each
distribution of interest income or principal on the participant's Units
(principal only in the case of a Unitholder who has chosen to reinvest only
principal distributions) will, on the applicable distribution date, or the next
day on which the New York Stock Exchange is nominally open ("BUSINESS DAY"), if
the distribution date is not a business day, automatically be received by the
transfer agent for each of the Accumulation Funds, on behalf of such participant
and applied on that date to purchase shares (or fractions thereof) of the
Accumulation Fund chosen at net asset value as computed as of 4:00 p.m. eastern
time on each such date. All distributions will be reinvested in the Accumulation
Fund chosen and no part thereof will be retained in a separate account. These
purchases will be made without a sales charge.

     The Transfer Agent of the Accumulation Fund will mail to each participant
in the Accumulation Plan a quarterly statement containing a record of all
transactions involving purchases of Accumulation Fund shares (or fractions
thereof) with Trust dividend distributions or as a result of reinvestment of
Accumulation Fund

                                      S-3

<PAGE>

dividends. Any distribution of capital used to purchase shares of an
Accumulation Fund will be separately confirmed by the Transfer Agent.
Unitholders will also receive distribution statements from the Trustee detailing
the amounts transferred to their Accumulation Fund accounts.

     Participants may at any time, by so notifying the Trustee in writing, elect
to change the Accumulation Fund into which their distributions are being
reinvested, to change from capital only reinvestment to reinvestment of both
capital and dividends or vice versa, or to terminate their participation in the
Accumulation Plan altogether and receive future distributions on their Units in
cash.  There will be no charge or other penalty for such change of election or
termination.  The character of Trust distributions for income tax purposes will
remain unchanged even if they are reinvested in an Accumulation Fund.

INFORMATION ABOUT THE SPONSOR

    Since our founding in 1898, Nuveen has been synonymous with investments that
withstand the test of time. Today, we offer a broad range of investments
designed for investors seeking to build and sustain their wealth. More than 1.5
million investors have entrusted Nuveen to help them maintain the lifestyle they
currently enjoy.

     To meet the unique circumstances and financial planning needs of our
investors, Nuveen offers a wide array of taxable and tax-free investment
products--including equity and fixed-income mutual funds, defined portfolios,
exchange-traded funds, customized asset management services and cash management
products.

     The Sponsor is also principal underwriter of the registered open-end
investment companies set forth herein under "Accumulation Plan" as well as for
the Golden Rainbow A James Advised Mutual Fund, and acted as co-managing
underwriter of Nuveen Municipal Value Fund, Inc., Nuveen California Municipal
Value Fund, Inc., Nuveen New York Municipal Value Fund, Inc., Nuveen Municipal
Income Fund, Inc., Nuveen Premium Income Municipal Fund, Inc., Nuveen
Performance Plus Municipal Fund, Inc., Nuveen California Performance Plus
Municipal Fund, Inc., Nuveen New York Performance Plus Municipal Fund, Inc.,
Nuveen Municipal Advantage Fund, Inc., Nuveen Municipal Market Opportunity Fund,
Inc., Nuveen California Municipal Market Opportunity Fund, Inc., Nuveen
Investment Quality Municipal Fund, Inc., Nuveen California Investment Quality
Municipal Fund, Inc., Nuveen New York Investment Quality Municipal Fund, Inc.,
Nuveen Insured Quality Municipal Fund, Inc., Nuveen Florida Investment Quality
Municipal Fund, Nuveen Pennsylvania Investment Quality Municipal Fund, Nuveen
New Jersey Investment Quality Municipal Fund, Inc., Nuveen Select Quality
Municipal Fund, Inc., Nuveen California Select Quality Municipal Fund, Inc.,
Nuveen New York Select Quality Municipal Fund, Inc., Nuveen Quality Income
Municipal Fund, Inc., Nuveen Insured Municipal Opportunity Fund, Inc., Nuveen
Florida Quality Income Municipal Fund, Nuveen Michigan Quality Income Municipal
Fund, Inc., Nuveen Ohio Quality Income Municipal Fund, Inc., Nuveen Texas
Quality Income Municipal Fund, Nuveen California Quality Income Municipal Fund,
Inc., Nuveen New York Quality Income Municipal Fund, Inc., Nuveen Premier
Municipal Income Fund, Inc., Nuveen Premier Insured Municipal Income Fund, Inc.,
Nuveen Select Tax-Free Income Portfolio, Nuveen Select Tax-Free Income Portfolio
2, Nuveen Insured California Select Tax-Free Income Portfolio, Nuveen Insured
New York Select Tax-Free Income Portfolio, Nuveen Premium Income Municipal Fund
2, Inc., Nuveen Select Tax-Free Income Portfolio 3, Nuveen Select Maturities
Municipal Fund, Nuveen Insured California Premium Income Municipal Fund, Inc.,
Nuveen Arizona Premium Income Municipal Fund, Inc., Nuveen Insured Florida
Premium Income Municipal Fund, Nuveen Michigan Premium Income Municipal Fund,
Inc., Nuveen New Jersey Premium

                                      S-4
<PAGE>

Income Municipal Fund, Inc., Nuveen Insured New York Premium Income Municipal
Fund, Inc., Nuveen Premium Income Municipal Fund 4, Inc., Nuveen Pennsylvania
Premium Income Municipal Fund 2, Nuveen Maryland Premium Income Municipal Fund,
Nuveen Virginia Premium Income Municipal Fund, Nuveen Massachusetts Premium
Income Municipal Fund, Nuveen Insured California Premium Income Municipal Fund
2, Inc., Nuveen Georgia Premium Income Municipal Fund, Nuveen Missouri Premium
Income Municipal Fund, Nuveen Connecticut Premium Income Municipal Fund, Nuveen
North Carolina Premium Income Municipal Fund, Nuveen California Premium Income
Municipal Fund, Nuveen Dividend Advantage Municipal Fund, Nuveen California
Dividend Advantage Municipal Fund, Nuveen New York Dividend Advantage Municipal
Fund, Nuveen Insured Premium Income Municipal Fund 2, all registered closed-end
management investment companies. These registered open-end and closed-end
investment companies currently have approximately $35 billion in securities
under management. Nuveen is a subsidiary of The John Nuveen Company which, in
turn, is approximately 78% owned by the St. Paul Companies, Inc. ("ST. PAUL").
St. Paul is located in St. Paul, Minnesota and is principally engaged in
providing property-liability insurance through subsidiaries. Nuveen is a member
of the National Association of Securities Dealers, Inc. and the Securities
Industry Association and has its principal office located in Chicago (333 West
Wacker Drive). Nuveen maintains 6 regional offices.

     To help advisors and investors better understand and more efficiently use
an investment in the Trust to reach their investment goals, the Trust's sponsor,
John Nuveen & Co. Incorporated, may advertise and create specific investment
programs and systems. For example, such activities may include presenting
information on how to use an investment in the Trust, alone or in combination
with an investment in other mutual funds or unit investment trusts sponsored by
Nuveen, to accumulate assets for future education needs or periodic payments
such as insurance premiums. The Trust's sponsor may produce software or
additional sales literature to promote the advantages of using the Trust to meet
these and other specific investor needs.

     The Sponsor offers a program of advertising support to registered
broker-dealer firms, banks and bank affiliates ("Firms") that sell Trust Units
or shares of Nuveen Open-End Mutual Funds (excluding money-market funds)
("Funds").  Under this program, the Sponsor will pay or reimburse the Firm for
up to one half of specified media costs incurred in the placement of
advertisements which jointly feature the Firm and the Nuveen Funds and Trusts.
Reimbursements to the Firm will be based on the number of the Firm's registered
representatives who have sold Fund Shares and/or Trust Units during the prior
calendar year according to an established schedule. Reimbursements under this
program will be made by the Sponsor and not by the Funds or Trusts.

RISK FACTORS

     An investment in Units should be made with an understanding of the risks
which an investment in common stocks entails, including the risk that the
financial condition of the issuers of the Securities or the general conditions
of the common stock market may worsen and the value of the Securities and
therefore the value of the Units may decline. Common stocks are especially
susceptible to general stock market movements and to volatile increases and
decreases of value as market confidence in and perceptions of the issuers
change. These perceptions are based on unpredictable factors including
expectations regarding government, economic, monetary and fiscal policies,
inflation and interest rates, economic expansion or contraction, and global or
regional political, economic or banking crises. Shareholders of common stocks
have rights to receive payments from the issuers of those common stocks that are
generally subordinate to those of creditors of, or holders of debt obligations
or preferred stocks of, such issuers. Shareholders of common stocks of the type
held by the Trust(s) have a right to receive dividends only when and if, and in
the amounts, declared by the issuer's board of directors and have a right to
participate in amounts available for distribution by the issuer only after all
other claims on the issuer have been paid or provided for. Common stocks do not
represent an obligation of the issuer and, therefore, do not offer any assurance
of income or provide the same degree of protection of capital as do debt
securities. The issuance of additional debt securities or preferred stock will
create prior claims for payment of principal, interest and dividends which could
adversely affect the ability and inclination of the issuer to declare or pay
dividends on its common stock or the rights of holders of common stock with
respect to assets of the issuer upon liquidation or bankruptcy. The value of
common stocks is subject to market fluctuations for as long as the common stocks
remain outstanding, and thus the value of the Securities in a Trust may be
expected to fluctuate over the life of a Trust to values higher or lower than
those prevailing on the Initial Date of Deposit.

     Holders of common stock incur more risk than holders of preferred stocks
and debt obligations because common stockholders, as owners of the entity, have
generally inferior rights to receive payments from the issuer in comparison with
the rights of creditors of, or holders of debt obligations or preferred stocks
issued by, the issuer. Cumulative preferred stock dividends must be paid before
common stock dividends and any cumulative preferred stock dividend omitted is
added to future dividends payable to the holders of cumulative preferred stock.
Preferred stockholders are also generally entitled to rights on liquidation
which are senior to those of common stockholders.

     Unitholders will be unable to dispose of any of the Securities in a Trust
and will not be able to vote the Securities. As the holder of the Securities,
the Trustee will have the right to vote all of the voting stocks in a Trust and
will vote such stocks in accordance with the instructions of the Sponsor.

     The value of the Securities will fluctuate over the life of a Trust and may
be more or less than the value at the time they were deposited in such Trust.
The Securities may appreciate or depreciate in value (or pay dividends)
depending on the full range of economic and market influences affecting these
Securities, including the impact of the Sponsor's purchase and sale of
Securities (especially during the primary offering period of Units of a Trust
and during the Special Redemption and Liquidation Period) and other factors.

     Whether or not the Securities are listed on a securities exchange, the
principal trading market for the Securities may be in the over-the-counter
market. As a result, the existence of a liquid trading market for the Securities
may depend on whether dealers will make a market in the Securities. There can be
no assurance that a market will be made for any of the Securities, that any
market for the Securities will be maintained or of the liquidity of the
Securities in any markets made. In addition, the Trust may be restricted under
the Investment Company Act of 1940 from selling Securities to the Sponsor. The
price at which the Securities may be sold to meet redemptions and the value of a
Trust will be adversely affected if trading markets for the Securities are
limited or absent. There can be no assurance that a Trust or successive trusts
that employ the same or a similar investment strategy will achieve their
investment objectives.


  Legislation. At any time after the Initial Date of Deposit, legislation may
be enacted, with respect to the Securities in a Trust or the issuers of the
Securities. Changing approaches to regulation, particularly with respect to the
environment or with respect to the petroleum or tobacco industry, may have a
negative impact on certain companies represented in a Trust. There can be no
assurance that future legislation, regulation or deregulation will not have a
material adverse effect on a Trust or will not impair the ability of the issuers
of the Securities to achieve their business goals.

                                      S-5


<PAGE>

                                  APPENDIX A
               STANDARD & POOR'S EARNINGS AND DIVIDEND RANKINGS
                               FOR COMMON STOCKS


     The investment process involves assessment of various factors--such as
products and industry position, corporate resources and financial policy--with
results that make some common stocks more highly esteemed than others.  In this
assesment, Standard & Poor's believes that earnings and dividend performance is
the end result of the interplay of these factors and that, over the long run,
the record of this performance has a considerable bearing on relative quality.
The rankings, however, do not pretend to reflect all of the factors, tangible or
intangible, that bear on stock quality.

     Relative quality of bonds or other debt, that is, degrees of protection for
principal and interest, called credit worthiness, cannot be applied to common
stocks, and therefore rankings are not to be confused with bond quality ratings
which are arrived at by a necessarily different approach.

     Growth and stability of earnings and dividends are deemed key elements in
establishing Standard & Poor's earnings and dividend rankings for common stocks.
It should be noted, however, that the process also takes into consideration
certain adjustments and modifications deemed desirable in establishing such
rankings.

     The major driver of these rankings is a computerized scoring system based
on per-share earnings and dividend records of the most recent ten years--a
period deemed long enough to measure significant time segments of secular
growth, to capture indications of basic changes in trend as they develop, and to
encompass the full peak-to-peak range of the business cycle.  Basic scores are
computed for earnings and dividends, then adjusted as indicated by a set of
predetermined modifiers for growth, stability within long-term trend, and
cyclicality.  Adjusted scores for earnings and dividends are then combined to
yield a final score.

     In addition, the ranking system makes allowance for the fact that, in
general, corporate size imparts certain recognized advantages from an investment
standpoint.  Conversely, minimum size limits (as measured by corporate revenues)
are set for the various rankings, but the system provides for exceptions when
the score reflects an outstanding earnings-dividend record.

     The final score for each stock is measured against a scoring matrix
determined by analysis of the scores of a large and representative sample of
stocks.  The range of scores in the array of this sample has been aligned with
the following ladder of rankings:

<TABLE>
<S>    <C>         <C>    <C>               <C>    <C>
A+     Highest     A-     Above Average     B-     Lower
A      High        B+     Average           C      Lowest
                   B      Below Average     D      In Reorganization
</TABLE>

     NR signifies no ranking because of insufficient data or because the stock
is not amenable to the ranking process.

     The rankings as determined above may be modified in some instances by
special considerations, such as natural disasters, massive strikes, and
non-recurring accounting adjustments.

     A ranking is not a forecast of future market price performance, but is
basically an appraisal of past performance of earnings and dividends, and
relative current standing.  These rankings must not be used as market
recommendations; a high-scoring stock may at times be so overpriced as to
justify its sale, while a low-scoring stock may be attractively priced for
purchase.  Rankings based upon earnings and dividend records are no substitute
for complete analysis.  They cannot take into account potential effects on
management changes, internal company policies not yet fully reflected in the
earnings and dividend record, public relations standing, recent competitive
shifts, and a host of other factors that may be relevant to market price or
suitability.

                                      A-1
<PAGE>

                                  APPENDIX B
                 STANDARD & POOR'S CORPORATE RATINGS CRITERIA


     A Standard & Poor's issue credit rating is a current opinion of the
creditworthiness of an obligor with respect to a specific financial obligations,
a specific class of financial obligations, or a specific financial program
(including ratings on medium-term note programs and commercial paper programs).
It takes into consideration the creditworthiness of guarantors, insurers, or
other forms of credit enhancement on the obligation and takes into account the
currency in which the obligation is denominated. The issue credit rating is not
a recommendation to purchase, sell, or hold a financial obligation, inasmuch
as it does not comment as to market price or suitability for a particular
investor.

     Issue credit ratings are based on current information furnished by the
obligors or obtained by Standard & Poor's from other sources it considers
reliable.  Standard & Poor's does not perform an audit in connection with any
credit rating and may, on occasion, rely on unaudited financial information.
Credit ratings may be changed, suspended, or withdrawn as a result of changes
in, or unavailability of, such information, or based on other circumstances.

     Issue credit ratings can be either long-term or short-term. Short-term
ratings are generally assigned to those obligations considered short-term in the
relevant market. In the U.S., for example, that means obligations with an
original maturity of no more than 365 days--including commercial paper. Short-
term ratings are also used to indicate the creditworthiness of an obligor with
respect to put features on long-term obligations. The result is a dual rating,
in which the short-term rating addresses the put feature, in addition to the
usual long-term rating. Medium-term notes are assigned long-term ratings.

LONG-TERM ISSUE CREDIT RATINGS

     Issue credit ratings are based, in varying degrees, on the following
considerations:

          1.  Likelihood of payment--capacity and willingness of the obligor to
     meet its financial commitment on an obligation in accordance with the terms
     of the obligation;

          2.  Nature of and provisions of the obligation; and

          3.  Protection afforded by, and relative position of, the obligation
     in the event of bankruptcy, reorganization, or other arrangement under the
     laws of bankruptcy and other laws affecting creditors' rights.

     The issue rating definitions are expressed in terms of default risk. As
such, they pertain to senior obligations of an entity.  Junior obligations are
typically rated lower than senior obligations, to reflect the lower priority in
bankruptcy, as noted above.  (Such differentiation applies when an entity has
both senior and subordinated obligations, secured and unsecured obligations, or
operating company and holding company

                                      B-1
<PAGE>

obligations.) Accordingly, in the case of junior debt, the rating may not
conform exactly with the category definition.

  "AAA"   An obligation rated "AAA" has the highest rating assigned by Standard
          & Poor's. The obligor's capacity to meet its financial commitment on
          the obligation is extremely strong.

   "AA"   An obligation rated "AA" differs from the highest rated obligations
          only in small degree. The obligor's capacity to meet its financial
          commitment on the obligation is very strong.

    "A"   An obligation rated "A" is somewhat more susceptible to the adverse
          effects of changes in circumstances and economic conditions than
          obligations in higher rated categories. However, the obligor's
          capacity to meet its financial commitment on the obligation is still
          strong.

  "BBB"   An obligation rated "BBB" exhibits adequate protection parameters.
          However, adverse economic conditions or changing circumstances are
          more likely to lead to a weakened capacity of the obligor to meet its
          financial commitment on the obligation.

     Obligations rated "BB," "B," "CCC," "CC," and "C" are regarded as having
significant speculative characteristics. "BB" indicates the least degree of
speculation and "C" the highest. While such obligations will likely have some
quality and protective characteristics, these may be outweighed by large
uncertainties or major exposures to adverse conditions.


   "BB"   An obligation rated "BB" is less vulnerable to nonpayment than other
          speculative issues. However, it faces major ongoing uncertainties or
          exposure to adverse business, financial, or economic conditions which
          could lead to the obligor's inadequate capacity to meet its financial
          commitment on the obligation.

    "B"   An obligation rated "B" is more vulnerable to nonpayment than
          obligations rated "BB," but the obligor currently has the capacity to
          meet its financial commitment on the obligation. Adverse business,
          financial, or economic conditions will likely impair the obligor's
          capacity or willingness to meet its financial commitment on the
          obligation.

  "CCC"   An obligation rated "CCC" is currently vulnerable to nonpayment, and
          is dependent upon favorable business, financial, and economic
          conditions for the obligor to meet its financial commitment on the
          obligation. In the event of adverse business, financial, or economic
          conditions, the obligor is not likely to have the capacity to meet its
          financial commitment on the obligation.

   "CC"   An obligation rated "CC" is currently highly vulnerable to nonpayment.

    "C"   The "C" rating may be used to cover a situation where a bankruptcy
          petition has been filed or similar action has been taken, but payments
          on this obligation are being continued.

    "D"   An obligation rated "D" is in payment default. The "D" rating category
          is used when payments on an obligation are not made on the date due
          even if the applicable grace period has not expired, unless Standard &
          Poor's believes that such payments will be made during such grade
          period. The "D" rating also will be used upon the filing of a
          bankruptcy petition or the taking of a similar action if payments on
          an obligation are jeopardized.

Plus(+) or minus (-): The ratings from "AA" to "CCC" may be modified by the
          addition of a plus or minus sign to show relative standing within the
          major rating categories.

     r    This symbol is attached to the ratings of instruments with significant
          noncredit risks. It highlights risks to principal or volatility of
          expected returns which are NOT addressed in the credit rating.
          Examples include: obligations linked or indexed to equities,
          currencies, or commodities; obligations exposed to severe prepayment
          risk--such as interest-only or principal-only mortgage securities; and
          obligations with unusually risky interest terms, such as inverse
          floaters.

                                      B-2

<PAGE>



                       Contents of Registration Statement

A.  Bonding Arrangements of Depositor:

          The Depositor has obtained the following Stockbrokers Blanket Bonds
    for its officers, directors and employees:

          Insurer/Policy No.                                 Amount

          Reliance Insurance Company
          B 262 6895                                       $26,000,000

B.  This amendment to the Registration Statement comprises the following papers
    and documents:
                                The facing sheet

                                 The Prospectus

                                 The signatures

                            Consents of Independent Public
                     Accountants and Counsel as indicated

                        Exhibits as listed on page S-5

C.   Explanatory Note

     This amendment to the Registration Statement may contain multiple separate
prospectuses. Each prospectus will relate to an individual unit investment trust
and will consist of a Part A, a Part B and an Information Supplement. Each
prospectus will be identical with the exception of the respective Part A which
will contain the financial information specific to such underlying unit
investment trust.

D.   Undertakings


     1.  The Information Supplement to the Trust(s) will not include third party
financial information.

                                      S-1
<PAGE>

                                  Signatures

     The Registrant, Nuveen Unit Trusts, Series 91 hereby identifies Series 94,
Series 82, Series 75, Series 66, Series 65, Series 63, Series 61, Series 53,
Series 52, Series 51, Series 50, Series 46, Series 43, Series 39, Series 38,
Series 37, Series 36, Series 35, Series 33, Series 4 and Series 1 of the Nuveen
Unit Trusts for purposes of the representations required by Rule 487 and
represents the following:

     (1) that the portfolio securities deposited in the series as to the
securities of which this Registration Statement is being filed do not differ
materially in type or quality from those deposited in such previous series;

     (2) that, except to the extent necessary to identify the specific portfolio
securities deposited in, and to provide essential financial information for, the
series with respect to the securities of which this Registration Statement is
being filed, this Registration Statement does not contain disclosures that
differ in any material respect from those contained in the registration
statements for such previous series as to which the effective date was
determined by the Commission or the staff; and

     (3) that it has complied with Rule 460 under the Securities Act of
1933.

     Pursuant to the requirements of the Securities Act of 1933, the Registrant,
Nuveen Unit Trusts, Series 91 has duly caused this Amendment of Registration
Statement to be signed on its behalf by the undersigned thereunto duly
authorized in the City of Chicago and State of Illinois on the 15th day of
May, 2000.
                                        NUVEEN UNIT TRUSTS, SERIES 91
                                                (Registrant)

                                        By JOHN NUVEEN & CO. INCORPORATED
                                                   (Depositor)

                                        By /s/ Thomas C. Muntz
                                           ------------------------------------
                                           Vice President

                                        Attest   Nicholas Dalmaso
                                               --------------------------------
                                               Assistant Secretary

                                      S-2
<PAGE>

     Pursuant to the requirements of the Securities Act of 1933, this Amendment
to the Registration Statement has been signed below by the following persons in
the capacities and on the date indicated:


<TABLE>
<CAPTION>
     Signature                       Title*                         Date
     ---------                       ------                         ----
<S>                          <C>                             <C>
Timothy R. Schwertfeger      Chairman, Board of Directors,)
                             Chief Executive Officer      )  Jessica R. Droeger
                             and Director                 )  ------------------
                                                          )  Jessica R. Droeger
John P. Amboian              President and Director       )  Attorney-in-Fact**
                                                          )
                                                          )
Margaret E. Wilson           Vice President and           )  May 15, 2000
                             Controller                   )
</TABLE>

- ---------

*  The titles of the persons named herein represent their capacity in and
relationship to John Nuveen & Co. Incorporated, the Depositor.

** The powers of attorney for Messrs. Amboian and Schwertfeger and for Ms.
Wilson were filed on May 3, 2000 as Exhibit 6.2 to Nuveen Unit Trusts, Series 94
(File No. 333-35488).

                                      S-3
<PAGE>


                   Consent of Independent Public Accountants

The consent of Arthur Andersen LLP to the use of its name in the Prospectus
included in the Registration Statement is filed by this amendment as Exhibit 4.4
to the Registration Statement.

                         Consent of Chapman and Cutler

The consent of Chapman and Cutler to the use of its name in the Prospectus
included in the Registration Statement is contained in its opinions filed by
this amendment as Exhibits 3.1 and 3.2 to the Registration Statement.

                      Consent of The Chase Manhattan Bank

The consent of The Chase Manhattan Bank to the use of its name in the Prospectus
included in the Registration Statement is filed by this amendment as Exhibit 4.2
to the Registration Statement.

                     Consent of Carter, Ledyard & Milburn

The consent of Carter, Ledyard & Milburn to the use of its name in the
Prospectus included in the Registration Statement is filed by this amendment as
Exhibit 3.3 to the Registration Statement.

                                      S-4
<PAGE>



                               List of Exhibits

1.1(a)  Copy of Standard Terms and Conditions of Trust for Nuveen Unit Trusts,
        Series 4 and certain subsequent series, effective May 29, 1997 between
        John Nuveen & Co. Incorporated, Depositor and The Chase Manhattan Bank,
        Trustee (incorporated by reference to Amendment No. 1 to Form S-6 [File
        No. 333-25225] filed on May 29, 1997 on behalf of Nuveen Unit Trusts,
        Series 4).

1.1(b)  Trust Indenture and Agreement.

1.2     Copy of Certificate of Incorporation, as amended, of John Nuveen & Co.
        Incorporated, Depositor (incorporated by reference to Form N-8B-2 [File
        No. 811-1547] filed on September 29, 1967 on behalf of Nuveen Tax-Exempt
        Unit Trust, Series 16).

1.3     Copy of amendment of Certificate of Incorporation changing name of
        Depositor to John Nuveen & Co. Incorporated (incorporated by reference
        to Form N-8B-2 [File No. 811-2198] filed on April 11, 1985 on behalf of
        Nuveen Tax-Exempt Unit Trust, Series 37).

2.1     Copy of Certificate of Ownership (included in Exhibit 1.1(a) on pages 2
        to 8, inclusive, and incorporated herein by reference).

2.2     Copy of Code of Ethics of the Trust(s) and the Principal Underwriter
        (incorporated by reference to Amendment No. 3 to Form S-6 [File No.
        333-96279] filed on March 6, 2000 on behalf of Nuveen Unit Trusts,
        Series 82).

3.1     Opinion of counsel as to legality of securities being registered.

3.2     Opinion of counsel as to Federal income tax status of securities being
        registered.

3.3     Opinion of counsel as to New York income tax status of securities being
        registered.

3.4     Opinion of counsel as to the Trustee and the Trust(s).

4.2     Consent of The Chase Manhattan Bank.

4.4     Consent of Arthur Andersen LLP.

6.1     List of Directors and Officers of Depositor and other related
        information (incorporated by reference to Exhibit E to Form N-8B-2
        [File No. 811-08103] filed on March 20, 1997 on behalf of Nuveen Unit
        Trusts, Series 1 and subsequent Series).

                                      S-5

<PAGE>

                                                                  Exhibit 1.1(b)

                         Nuveen Unit Trusts, Series 91
                         Trust Indenture and Agreement

                              Dated: May 15, 2000

     This Trust Indenture and Agreement by and between John Nuveen & Co.
Incorporated, as Depositor and The Chase Manhattan Bank, as Trustee, sets forth
certain provisions in full and incorporates other provisions by reference to the
document entitled "Standard Terms and Conditions of Trust for Nuveen Unit Trust,
Series 4 and certain subsequent Series, effective May 29, 1997" (herein called
the "Standard Terms and Conditions of Trust"), and such provisions as are set
forth in full and such provisions as are incorporated by reference constitute a
single instrument. All references herein to Articles and Sections are to
Articles and Sections of the Standard Terms and Conditions of Trust.

                               Witnesseth That:

     In consideration of the promises and of the mutual agreements herein
contained, the Depositor and the Trustee agree as follows:

                                    Part I

                    Standard Terms and Conditions of Trust

     Subject to the Provisions of Part II hereof, all the provisions contained
in the Standard Terms and Conditions of Trust are herein incorporated by
reference in their entirety and shall be deemed to be a part of this instrument
as fully and to the same extent as though said provisions had been set forth in
full in this instrument.

                                    Part II

                     Special Terms and Conditions of Trust

     The following special terms and conditions are hereby agreed to:

          (a)  The Securities defined in Section 1.01(1) listed in Schedule A
     hereto have been deposited in trust under this Trust Indenture and
     Agreement.

          (b) The fractional undivided interest in and ownership of the Trust
     Fund represented by each Unit for the Trust(s) on the Initial Date of
     Deposit is 1/(the number of Units) set forth under the caption
     "Statement(s) of Condition--Interest of Unitholders: Units of fractional
     undivided interest outstanding" in the Prospectus.
<PAGE>

          (c) The number(s) of Units created of the Trust(s) are as set forth
     under the caption "Statement(s) of Condition--Interest of Unitholders:
     Units of fractional undivided interest outstanding" in the Prospectus for
     the Trust(s).
          (d)  Section 10.02 shall be amended to read in its entirety as
     follows:

          Section 10.02. Initial Costs. Subject to reimbursement as hereinafter
provided, the cost of organizing the Trust(s) and the sale of the Trust Units
shall be borne by the Depositor, provided, however, that the liability on the
part of the Depositor under this section shall not include any fees or other
expenses incurred in connection with the administration of the Trust(s)
subsequent to the deposit referred to in Section 2.01. At the earlier of six
months after the Initial Date of Deposit or the conclusion of the primary
offering period (as certified by the Depositor to the Trustee), the Trustee
shall withdraw from the Account or Accounts specified in the Prospectus or, if
no Account is therein specified, from the Capital Account, and pay to the
Depositor the Depositor's reimbursable expenses of organizing the Trust(s) in an
amount certified to the Trustee by the Depositor. In no event shall the amount
paid by the Trustee to the Depositor for the Depositor's reimbursable expenses
of organizing the Trust(s) exceed the estimated per Unit amount of organization
costs set forth in the prospectus for the Trust(s) multiplied by the number of
Units of the Trust(s) outstanding at the earlier of six months after the Initial
Date of Deposit or the end of the initial offering period; nor shall the
Depositor be entitled to or request reimbursement for expenses of organizing the
Trust(s) incurred after the earlier of six months after the Initial Date of
Deposit or the end of the initial offering period. If the cash balance of the
Capital Account is insufficient to make such withdrawal, the Trustee shall, as
directed by the Depositor, sell Securities identified by the Depositor, or
distribute to the Depositor Securities having a value, as determined under
Section 4.01 as of the date of distribution, sufficient for such reimbursement.
Securities sold or distributed to the Depositor to reimburse the Depositor
pursuant to this Section shall be sold or distributed by the Trustee to the
extent practicable, in the percentage ratio then existing (unless the Trust
elects to be treated as a "regulated investment company" as defined in the
United States Internal Revenue Code (the "Internal Revenue Code") in which case
sales or distributions by the Trustee shall be made in accordance with the
instructions of the Depositor or its designees). The reimbursement provided for
in this section shall be for the account of the Unitholders of record at the
earlier of six months after the Initial Date of Deposit or the conclusion of the
primary offering period. Any assets deposited with the Trustee in respect of the
expenses reimbursable under this Section 10.02 shall be held and administered as
assets of the Trust(s) for all purposes hereunder. The Depositor shall deliver
to the Trustee any cash identified in the Statement(s) of Condition of the
Trust(s) included in the Prospectus not later than the 10 calendar days
following the Initial Date of Deposit or deposit of additional Securities, as
applicable and the Depositor's obligation to make such delivery shall be secured
by the letter of credit deposited pursuant to Section 2.01. Any cash which the
Depositor has identified as to be used for reimbursement of expenses pursuant to
this Section 10.02 shall be held by the Trustee, without interest, and reserved
for such purpose and accordingly, prior to the earlier of six months after the
Initial Date of Deposit or the conclusion of the primary offering period, shall
not be subject to distribution or, unless the Depositor otherwise directs, used
for payment of redemptions in excess of the per Unit amount payable pursuant to
the next sentence. If a Unitholder redeems Units prior to the earlier of six
months after the Initial Date of Deposit or the conclusion of the primary
offering period, the Trustee shall pay to the Unitholder, in addition to the
Redemption Value of the tendered Units, unless otherwise directed by the
Depositor, an amount equal to the estimated per Unit cost of organizing the
Trust(s) set forth in the Prospectus, or such lower revision thereof most
recently communicated to the Trustee by the Depositor pursuant to Section 5.01,
multiplied by the number of Units tendered for redemption; to the extent the
cash on hand in the Trust(s) is insufficient for such payment, the Trustee shall
have the power to sell Securities in accordance with Section 5.02. As used
herein, the Depositor's reimbursable expenses of organizing the Trust(s) shall
include the cost of the initial preparation and typesetting of the registration
statement, prospectuses (including preliminary prospectuses), the indenture, and
other documents relating to the Trust(s), SEC and state blue sky registration
fees, the cost of the initial valuation of the portfolio and audit of the
Trust(s), the initial fees and expenses of the Trustee, and legal and other out-
of-pocket expenses related thereto, but not including the expenses incurred in
the printing of preliminary prospectuses and prospectuses, expenses incurred in
the preparation and printing of brochures and other advertising materials and
any other selling expenses.

          (e) Article I of the Standard Terms and Conditions of Trust is hereby
     amended to replace the definitions of "Capital Distribution Date,"
     "Contract Securities," "Initial Date of Deposit," "Mandatory Termination
     Date," "Record Date," "Securities" and "Unit" and to add the following
     definitions:

          Capital Distribution Date

               The meaning assigned to it in the Prospectus for a Trust.

          Mandatory Termination Date

               The meaning assigned to it in the Prospectus for a Trust.

          Contract Securities

               The Securities which are to be acquired by any Trust Fund
          pursuant to a contract or contracts for the purchase of such
          securities which have been assigned to the Trustee along with the
          amounts required for their purchase which have been delivered to the
          Trustee.

          Evaluator

               The party designated in the Prospectus for a Trust or any party
          appointed by the Sponsor.

          Initial Date of Deposit

               The meaning assigned to it in the Prospectus for each respective
          Trust Fund.

          Prospectus

               The prospectus relating to a Trust in the form first used to
          confirm sales of Units.

          Record Date

               As applicable, the meaning assigned in "Income Record Date"
          and/or "Capital Record Date" in the Prospectus for each respective
          Trust Fund.

          Securities

               The securities, including Contract Securities listed in Schedule
          A to the Trust Agreement or other securities that may be deposited in
          a Trust Fund and any obligations received in exchange or substitution
          for such securities, as may from time to time continue to be held as a
          part of any Trust Fund.

          Unit

               The fractional undivided interest in and ownership of an
          individual Trust Fund equal initially to 1/(the number of Units of
          fractional undivided interest outstanding) provided in the Statement
          of Condition in the Prospectus for the Trust Fund, the denominator of
          which fraction shall be (1) increased by the number of any additional
          Units issued pursuant to Section 2.03 hereof and (2) decreased by the
          number of any such Units redeemed as provided in Section 5.02.
          Whenever reference is made herein to the "interest" of a Unitholder in
          the Trust Fund or in the Income or Capital Accounts, it shall mean
          such fractional undivided interest represented by the number of Units,
          whether or not evidenced by a Certificate or Certificates, held of
          record by such Unitholder in such Trust Fund.

                                      -2-
<PAGE>

                                                                       Ex.1.1(b)


               (f) The following shall be added at the end of the first
     paragraph of subsection (a) of Section 5.03:

          The notice and form of election to be sent to Unitholders in respect
     of any redemption and purchase of Units of a New Series as provided in this
     section shall be in such form and shall be sent at such time or times as
     the Depositor shall direct the Trustee in writing and the Trustee shall
     have no responsibility therefor. The Distribution Agent acts solely as
     disbursing agent in connection with purchases of Units pursuant to this
     Section and nothing herein shall be deemed to constitute the Distribution
     Agent a broker in such transactions.

               (g) Article III of the Standard Terms and Conditions of Trust is
     hereby amended to add the following section:

               Section 3.14. License Fees. If so provided in Part A of the
     Prospectus, the Depositor may enter into a Licensing Agreement (the
     "Agreement") with a licensor (the "Licensor") described in the Prospectus
     in which the Trust(s), as consideration for the licenses granted by the
     Licensor for the right to use its trademarks, trade names and/or service
     marks, intellectual property rights or for the use of databases and
     research owned by the Licensor, will pay a fee set forth in the Agreement
     to the applicable Licensor or the Depositor to reimburse the Depositor for
     payment of the expenses.

               If the Agreement provides for an annual license fee computed in
     whole or part by reference to the average daily net asset value of the
     Trust assets, for purpose of calculating the accrual of estimated expenses
     such annual fee shall accrue at a daily rate and the Trustee is authorized
     to compute an estimated license fee payment (i) until the Depositor has
     informed the Trustee that there will be no further deposits of additional
     Securities, by reference to an estimate of the average daily net asset
     value of the Trust assets which the Depositor shall provide the Trustee,
     (ii) thereafter and during the calendar quarter in which the last business
     day of the period described in clause (i) occurs, by reference to the net
     asset value of the Trust assets as of such last business day, and (iii)
     during each subsequent calendar quarter, by reference to the net asset
     value of the Trust assets as of the last business day of the preceding
     calendar quarter. The Trustee shall adjust the net asset value (Trust Fund
     Evaluation) as of the dates specified in the preceding sentence to account
     for any variation between accrual of estimated license fee and the license
     fee payable pursuant to the Agreement, but such adjustment shall not affect
     calculations made prior thereto and no adjustment shall be made in respect
     thereof.

               (h) The following subsection (d) shall be added to Section 7.02:

               (d) The Depositor may employ agents in connection with its duties
     under Section 3.11 and 3.13 hereof and shall not be answerable for the
     default or misconduct of such agents if they shall have been selected with
     reasonable care. The fees of such agents shall be reimbursable to the
     Depositor from the Trust Fund, provided, however, that the amount of such
     reimbursement in any year (i) shall reduce the amount payable to the
     Depositor for such year with respect to the service in question and shall
     not exceed the maximum amount payable to the Depositor for such service for
     such year and (ii) if such agent is an affiliate of the Depositor, the
     amount of the reimbursement, when combined with (a) all compensation
     received by such agent from other series of the Fund or other unit
     investment trusts sponsored by the Depositor or its affiliates and (b) the
     amount payable to the Depositor from the Trust Fund and from other series
     of the Fund or other unit investment trusts sponsored by the Depositor or
     its affiliates in respect of the service in question, shall not exceed the
     aggregate cost of such agent and the Depositor of providing such service.
     The Trustee shall pay such reimbursement against the Depositor's invoice
     therefor upon which the Trustee may rely as the Depositor's certification
     that the amount claimed complies with the provisions of this paragraph.

               (i)  Section 4.01 shall be amended to read in its entirety as
     follows:

               Section 4.01.  Evaluation of Securities. The Evaluator shall
     determine separately and promptly furnish to the Trustee and the Depositor
     upon request the value of each issue of Securities as of the Evaluation
     Time as provided in the following manner:

               (a) The Evaluator will prepare each evaluation for which market
quotations for the Securities are available by the use of outside services
normally used and contracted with for this purpose. If the Securities are listed
on a national or foreign securities exchange or The NASDAQ Stock Market, Inc.
the evaluation will be based on the closing sale price on the exchange or system
where the Securities are principally traded (if a Security is listed on the New
York Stock Exchange, the closing sale price on that exchange shall apply) or, if
there is no closing sale price on the exchange or system, at the closing bid
price on the exchange or system. If such market quotations are not available,
the Evaluator shall determine the value of the Securities. Such evaluation shall
generally be based on the current bid prices on the over-the-counter market
(unless it is determined that these prices are inappropriate as a basis for
evaluation). If such prices are not available on the over-the-counter market,
the evaluation will generally be made by the Evaluator in good faith (1) on the
basis of the current bid prices for comparable securities, (2) by the
Evaluator's appraising the value of the Securities in good faith at the bid side
of the market or (3) by any combination thereof. If such prices are in a
currency other than U.S. dollars, the Evaluation of such Security shall be
converted to U.S. dollars based on current bid site exchange rates, unless the
Security is in the form of an American Depositary Share or Receipt, in which
case the Evaluations shall be based upon the U.S. dollar prices in the market
for American Depositary Shares or Receipts (unless the Evaluator deems such
prices inappropriate as a basis for valuation). As used herein, the closing sale
price is deemed to mean the most recent closing sale price on the relevant
securities exchange immediately prior to the Evaluation Time.

               For each evaluation, the Evaluator shall also determine and
furnish to the Trustee and the Depositor the aggregate of (a) the value of all
Securities on the basis of such evaluation and (b) on the basis of the
information furnished to the Evaluator by the Trustee pursuant to Section 3.02,
the amount of cash then held in the Capital Account which was received by the
Trustee after the Record Date preceding such determination less any amounts held
in the Capital Account for distribution to Unitholders on a subsequent
Distribution Date when a Record Date occurs four business days or less after
such determination. For the purposes of the foregoing, the Evaluator may obtain
current prices for the Securities from investment dealers or brokers (including
the Depositor) that customarily deal in similar securities.

               With respect to any Security not listed on a national or foreign
exchange or The NASDAQ Stock Market, Inc., or, with respect to a Security so
listed but in the unusual circumstance in which the Evaluator deems the closing
sale price on the relevant exchange to be inappropriate as a basis for
valuation, upon the Evaluator's request, the Depositor shall, from time to time,
designate one or more evaluation services or other sources of information on
which the Evaluator shall be authorized conclusively to rely in evaluating such
Security. The Depositor shall also designate one or more banks (which may
include the Trustee) or other source of information from which the Evaluator
shall take foreign exchange rate quotations. The Evaluator shall have no
liability for any errors in the information received from any source
designated by the Depositor. The cost thereof shall be an expense reimbursable
to the Evaluator from the Income and Capital Accounts.

               (b) Notwithstanding Section 4.01(a), except in those cases in
which the Securities are listed on a national or foreign securities exchange or
The NASDAQ Stock Market, Inc., and the closing sales prices are used and except
for Trust Fund Evaluations required by Section 5.02 in determining Redemption
Price, during the initial offering period, the evaluations of the Securities
shall generally be made in the manner described in Section 4.01(a) based on the
closing ask prices of the Securities rather than the closing bid prices and on
current offering side exchange rates.

               (j)  Section 5.01 shall be amended to read in its entirety as
     follows:

               Section 5.01. Trust Fund Evaluation. As of the Evaluation Time
     next following any tender by a Unitholder for redemption and on any other
     business day desired by it or as may be required hereunder, the Trustee
     shall as to each Trust Fund:

     Add

               (1)  cash on hand in the Trust Fund (other than cash held
     especially for the purchase of Contract Securities) and moneys in the
     process of being collected from declared dividends,

               (2)  the aggregate value of each issue of the Securities in the
     Trust Fund (including Contract Securities) as determined by the Evaluator
     pursuant to Section 4.01, and

               (3)  all other assets of the Trust;

     Deduct

               (1)  amounts representing any applicable taxes, governmental
     charges or other charges pursuant to Section 3.03 payable out of the Trust
     Fund and for which no deductions shall have previously been made for the
     purpose of addition to the Reserve Account,

               (2) amounts representing estimated accrued fees and expenses of
     the Trust Fund including but not limited to unpaid Creation and Development
     Fees, unpaid fees and expenses of the Trustee (including legal and auditing
     expenses), the Evaluator, the Depositor and counsel, and

               (3)  amounts representing unpaid accrued organization costs, and

               (4)  cash allocated for distribution to Unitholders of the Trust
     Fund of record as of the business day prior to the evaluation then being
     made.

     The resulting figure is herein called a "Trust Fund Evaluation."

     Prior to the payment to the Depositor of its reimbursable organization
     costs to be made at the earlier of six months after the Initial Date of
     Deposit or the conclusion of the primary offering period in accordance with
     Section 10.02, for purposes of determining the Trust Fund Evaluation under
     this Section 5.01, the Trustee shall rely upon the amounts representing
     unpaid accrued organization costs in the estimated amount per Unit set
     forth in the Prospectus until such time as the Depositor notifies the
     Trustee in writing of a revised estimated amount per Unit representing
     unpaid accrued organization costs. Upon receipt of such notice, the Trustee
     shall use this revised estimated amount per Unit representing unpaid
     accrued organization costs in determining the Trust Fund Evaluation but
     such revision of the estimated expenses shall not affect calculations made
     prior thereto and no adjustment shall be made in respect thereof.

     Amounts receivable by the Trust(s) in a foreign currency shall be reported
     to the Evaluator who shall convert the same to U.S. dollars based on
     current exchange rates, in the same manner as provided in Section 4.01, for
     the conversion of the valuation of foreign Securities, and the Evaluator
     shall report such conversion with each Evaluation made pursuant to Section
     4.01.

               (k)  Notwithstanding anything to the contrary contained in
Sections 3.04, 3.11, 3.13, 4.03 and 8.05, expenses of the Trust shall be paid to
the appropriate party on or about the 15th day of each month. Until the Trustee
is notified by the Depositor that the primary offering period has terminated,
the fees, where applicable, shall be accrued daily and based on the number of
Units outstanding on each day.

After the primary offering period has terminated, the fees, where applicable,
shall accrue daily and be based on the number of Units outstanding on the most
recent prior Income Record Date specified in the Prospectus or the number of
Units outstanding at the end of the initial offering period, as
appropriate.

               (l)  Section 8.01(i) shall be amended to read in its entirety as
follows:

               (i) Notwithstanding any provisions of this Agreement to the
contrary, no payment to a Depositor or to any principal underwriter (as defined
in the Investment Company Act of 1940) for the Trust Fund or to any affiliated
person (as so defined) or agent of a Depositor or such underwriter shall be
allowed the Trustee as an expense except (a) for payment of such reasonable
amounts as the Securities and Exchange Commission may prescribe as compensation
for performing bookkeeping and other administrative services of a character
normally performed by the Trustee, and (b) such other amounts permitted under
the Investment Company Act of 1940.

               (m)  All references to the "NASDAQ National Market System" herein
and in the Standard Terms and Conditions of Trust shall be replaced with "The
NASDAQ Stock Market, Inc."

               (n)  The following shall replace the second paragraph of Section
5.03 in its entirety:

               All Units so tendered by a Unitholder (a "Rollover Unitholder")
shall be redeemed and cancelled on such date during the Special Redemption and
Liquidation Period as the Depositor shall determine and notify the Trustee
thereof. Subject to payment by such Rollover Unitholder of any tax or other
governmental charges which may be imposed thereon, such redemption is to be made
in kind pursuant to Section 5.02 by distribution of cash and/or Securities to
the Distribution Agent based on the net asset value on the date the Units are
redeemed and cancelled multiplied by the number of Units being redeemed (herein
called the "Rollover Distribution").

               (o)  Section 8.01 shall be amended to add the following as
paragraph (1):

                    (1)  The Trustee except by reason of its own negligence or
willful misconduct shall not be liable for any action taken or suffered to be
taken by it in good faith and believed by it to be authorized or within the
discretion or rights or powers conferred upon it by this Indenture.

               (p)  Section 3.06 shall be amended for each Trust that does not
elect to be treated as a "regulated investment company" as defined in the
Internal Revenue Code to read in its entirety as follows:

               Section 3.06.  Extraordinary Sale of Securities. If necessary, in
order to maintain the sound investment character of the Trust(s), the Depositor
may direct the Trustee to sell or liquidate Securities in such Trust at such
price and time and in such manner as shall be determined by the Depositor,
provided that the Depositor has determined that any one or more of the following
conditions exist:

               (a)  that there has been a default on any of the Securities in
the payment of dividends, after declared and when due and payable;

               (b)  that any action or proceeding has been instituted at law or
equity seeking to restrain or enjoin the payment of dividends on any such
Securities, or that there exists any legal question or impediment affecting such
Securities or the payment of dividends from the same;

               (c)  that there has occurred any breach of covenant or warranty
in any document relating to the issuer of the Securities which would adversely
affect either immediately or contingently the payment of dividends from such
Securities, or the general credit standing of the issuer or otherwise impair the
sound investment character of such Securities;

               (d)  that there has been a default in the payment of dividends,
principal of or income or premium, if any, on any other outstanding obligations
of the issuer of such Securities;

               (e)  that the price of any such Securities had declined to such
an extent or other such credit factors exist so that in the opinion of the
Depositor, as evidenced in writing to the Trustee, the retention of such
Securities would be detrimental to the Trust Fund and to the interest of the
Unitholders;

               (f)  that the sale of Securities is necessary or advisable in
order to maintain the qualification of the Trust as a "regulated investment
company" in the case of a Trust which has elected to qualify as such; and

               (g)  that there has been a public tender offer made for a
Security or a merger or acquisition is announced affecting a Security, and that
in the opinion of the Sponsor the sale or tender of the Security is in the best
interest of the Unitholders.

               Upon receipt of such direction from the Depositor, upon which the
Trustee shall rely, the Trustee shall proceed to sell or liquidate the specified
Securities in accordance with such direction, and upon the receipt of the
proceeds of any such sale or liquidation, after deducting therefrom any fees and
expenses of the Trustee connected with such sale or liquidation and any
brokerage charges, taxes or other governmental charges shall deposit such net
proceeds in the Capital Account.

               The Trustee shall not be liable or responsible in any way for
depreciation or loss incurred by reason of any sale made pursuant to any such
direction or by reason of the failure of the Depositor to give any such
direction, and in the absence of such direction the Trustee shall have no duty
to sell or liquidate any Securities under this Section 3.06 except to the extent
otherwise required by this Indenture. The Depositor shall not be liable for
errors of judgment in directing or failing to direct the Trustee pursuant to
this Section 3.06. This provision, however, shall not protect the Trustee or
Depositor against any liability for which they would otherwise be subject,
respectively, by reason of wilful misfeasance, bad faith or gross negligence in
the performance of their duties or by reason of their reckless disregard of
their obligations and duties hereunder.

               (q) Article III of the Standard Terms and Conditions of Trust is
hereby amended to add the following Section:

               Section 3.15. Creation and Development Fee. If the Prospectus
related to the Trust(s) specifies a Creation and Development Fee, the Trustee
shall, on the last day of each month, withdraw from the Capital Account an
amount equal to the accrued and unpaid Creation and Development Fee as of such
date and credit such amount to a special non-Trust account designated by the
Depositor out of which the Creation and Development Fee will be distributed to
the Depositor (the "Creation and Development Account"). The Creation and
Development Fee will accrue on a daily basis at an annual rate as set forth in
the Prospectus for the Trust(s) based on a percentage of the average daily net
asset value of the Trust(s). If the balance in the Capital Account is
insufficient to make such withdrawal, the Trustee shall, as directed by the
Depositor, advance funds in an amount required to fund the proposed withdrawal
and be entitled to reimbursement of such advance upon the deposit of additional
monies in the Capital Account, and/or sell Securities and credit the proceeds
thereof to the Creation and Development Account, provided, however, that the
aggregate amount advanced by the Trustee at any time for payment of the Creation
and Development Fee shall not exceed $15,000. Such direction shall, if the
Trustee is directed to sell a Security, identify the Security to be sold and
include instructions as to the execution of such sale. In the absence of such
direction by the Depositor, the Trustee shall sell Securities sufficient to pay
the Creation and Development Fee (and any unreimbursed advance then outstanding)
in full, and shall select Securities to be sold in such manner as will maintain
(to the extent practicable) the relative proportion of the number of shares of
each Security then held. The proceeds of such sales, less any amounts paid to
the Trustee in reimbursement of its advances, shall be credited to the Creation
and Development Account. If a Trust is terminated pursuant to Section 8.01(g),
the Depositor agrees to reimburse the Unitholders for any amounts of the
Creation and Development Fee collected by the Depositor to which it is not
entitled. All advances made by the Trustee pursuant to this Section shall be
secured by a lien on the Trust(s) prior to the interest of Unitholders.
Notwithstanding the foregoing, the Depositor shall not receive any amount of the
Creation and Development Fee which exceeds the maximum amount per Unit stated in
the Prospectus. The Depositor shall notify the Trustee not later than ten
business days prior to the date on which it anticipates that the maximum amount
of the Creation and Development Fee it may receive has been accrued and shall
also notify the Trustee as of the date when the maximum amount of the Creation
and Development Fee has been accrued. The Trustee shall have no responsibility
or liability for damages or loss resulting from any error in the information
provided by the Depositor, or the Depositor's failure to provide the
information, specified in the preceding sentence. The Depositor agrees to
reimburse the Trust(s) and any Unitholder any amount of the Creation and
Development Fee it receives which exceeds the amount which the Depositor may
receive under applicable laws, regulations and rules.

               (r) Paragraph (e) of Section 8.01 is amended to read as follows:

                    (e)  (I) Subject to the provisions of subparagraphs (II) and
     (III) of this paragraph, the Trustee may employ agents, sub-custodians,
     attorneys, accountants and auditors and shall not be answerable for the
     default or misconduct of any such agents, sub-custodians, attorneys,
     accountants or auditors if such agents, sub-custodians, attorneys,
     accountants or auditors shall have been selected with reasonable care. The
     Trustee shall be fully protected in respect of any action under this
     Indenture taken or suffered in good faith by the Trustee in accordance with
     the opinion of counsel, which may be counsel to the Depositor acceptable to
     the Trustee, provided, however, that this disclaimer of liability shall not
     (i) excuse the Trustee from the responsibilities specified in subparagraph
     II below or (ii) limit the obligation of the Trustee to indemnify the
     Trust(s) under subparagraph III below. The fees and expenses charged by
     such agents, sub-custodians, attorneys, accountants or auditors shall
     constitute an expense of the Trust(s) reimbursable from the Income and
     Capital Accounts of the affected Trust as set forth in section 8.05 and
     3.04 hereof.

                    (II) The Trustee may place and maintain in the care of an
     eligible foreign custodian (which is employed by the Trustee as a sub-
     custodian as contemplated by subparagraph (I) of this paragraph (e) and
     which may be an affiliate or subsidiary of the Trustee or any other entity
     in which the Trustee may have an ownership interest) a Trust's foreign
     securities, cash and cash equivalents in amounts reasonably necessary to
     effect the Trust's foreign securities transactions, provided that the
     Trustee hereby agrees to perform all the duties assigned by rule 17f-5 as
     now in effect or as it may be amended in the future, to the boards of
     directors of management investment companies. The Trustee's duties under
     the preceding sentence will not be delegated.

               As used in this subparagraph (II),

                    (1) "foreign securities" include: securities issued and sold
primarily outside the United States by a foreign government, a national of any
foreign country or a corporation or other organization incorporated or organized
under the laws of any foreign country and securities issued or guaranteed by the
government of the United States or by any state or any political subdivision
thereof or by any agency thereof or by any entity organized under the laws of
the United States or of any state thereof which have been issued and sold
primarily outside the United States.

                    (2) "eligible foreign custodian" means

                (a) The following securities depositories and clearing agencies
which operate transnational systems for the central handling of securities or
equivalent book entries which, by appropriate exemptive order issued by the
Securities and Exchange Commission, have been qualified as eligible foreign
custodians for the Trust(s) but only for so long as such exemptive order
continues in effect: the Euroclear System ("Euroclear"), and Cedel Bank S.A.
("CEDEL").

               (b) Any other entity that shall have been qualified as an
eligible foreign custodian for the foreign securities of the Trust(s) by the
Securities and Exchange Commission by exemptive order, rule or other appropriate
action, commencing on such date as it shall have been so qualified but only for
so long as such exemptive order, rule or other appropriate action continues in
effect.

                    (III) The Trustee will indemnify and hold the Trust(s)
harmless from and against any loss occurring as a result of an eligible foreign
custodian's willful misfeasance, reckless disregard, bad faith, or gross
negligence in performing custodial duties.

               (s) Section 2.01(c) is hereby amended by adding the following at
the conclusion thereof:

               If any Contract Obligation requires settlement in a foreign
     currency, in connection with the deposit of such Contract Obligation the
     Depositor will deposit with the Trustee either an amount of such currency
     sufficient to settle the contract or a foreign exchange contract in such
     amount which settles concurrently with the settlement of the Contract
     Obligation and cash or a Letter of Credit in U.S. dollars sufficient to
     perform such foreign exchange contract.

          (t) Article III of the Standard Terms and Conditions of Trust is
hereby amended to add the following section:

               Section 3.16. Foreign Currency Exchange. Unless the Depositor
     shall otherwise direct, whenever funds are received by the Trustee in
     foreign currency, upon the receipt thereof or, if such funds are to be
     received in respect of a sale of Securities, concurrently with the contract
     of the sale for the Security (in the latter case the foreign exchange
     contract to have a settlement date coincident with the relevant contract of
     sale for the Security), the Trustee shall enter into a foreign exchange
     contract for the conversion of such funds to U.S. dollars pursuant to the
     instruction of the Depositor. The Trustee shall have no liability for any
     loss or depreciation resulting from action taken pursuant to such
     instruction.

          (u) If so provided in the Prospectus for the Trust(s), each Trust
     elects to be treated and to qualify as a Regulated Investment Company as
     defined in the Internal Revenue Code, and the Trustee is hereby directed to
     make such elections, including any appropriate election to be taxed as a
     corporation, as shall be necessary to effect such qualification.

          (v) Section 8.01 shall be amended to add the following paragraph (m):

               (m) The Chase Manhattan Bank, or an affiliate, may, when
instructed by the Sponsor pursuant to Section 3.16 enter into foreign exchange
transactions with the Trust, with the same rights and powers as if The Chase
Manhattan Bank were not the Trustee hereunder.

          (w) The following is added to the end of the first paragraph of
Section 5.02.

               Sales of foreign securities shall be made in such manner and at
     such price as the Depositor, or its delegate, shall direct, and the Trustee
     shall not be liable or responsible for depreciation or loss incurred by
     reason of any sale made pursuant to such direction. If a Trust has elected
     to be taxed as a "regulated investment company," if Securities in the Trust
     are sold for the payment of the Redemption Price and there are excess
     proceeds remaining after meeting redemption requests, the Depositor or its
     designee may, but is not obligated to, direct the investment of such excess
     proceeds into any Securities included in the applicable index.

          (x) Section 3.12 is hereby amended by adding the following at the
conclusion thereof:

               The Depositor represents that the price paid by any Unitholder
     for Units acquired through reinvestment of Trust distributions will be
     reduced by the aggregate amount of unpaid deferred sales charges at the
     time of the purchase to offset any subsequent collection by the Depositor
     of deferred sales charges in respect of the Units so acquired.

          (y) If a Trust has elected to be treated as a "regulated investment
company" as defined in the Internal Revenue Code, subsection (b) of Section 2.01
shall be restated in its entirety as follows:

          (b) (1) From time to time following the Initial Date of Deposit for a
     Trust, the Depositor is hereby authorized, in its discretion, to assign,
     convey to and deposit with the Trustee (i) additional Securities for such
     Trust, duly endorsed in blank or accompanied by all necessary instruments
     of assignment and transfer in proper form, or (ii) Contract Securities
     relating to such additional Securities, accompanied by cash and/or
     Letter(s) of Credit as specified in paragraph (c) of this Section 2.01. In
     lieu of additional Securities or Contract Securities, the Depositor may
     deposit with the Trustee cash (or a Letter of Credit) in an amount equal to
     the valuation made in accordance with Section 4.01 for the date of such
     deposit of the additional Securities not delivered or represented by
     Contract Securities and the Depositor or its designated agent shall, on
     behalf of each Trust, enter into contracts to purchase such additional
     Securities and shall provide the Trustee such information as the Trustee
     may require in order to settle such transactions and take delivery of such
     additional Securities which the Trustee is hereby directed to do. If the
     Trust involved seeks to consist of securities included in a securities
     index, deposits of additional Securities shall consist of Securities
     included in the applicable index as determined by the Depositor or its
     designee. Any brokerage fees related to the purchase of Securities
     deposited in the Trust Fund after the Initial Date of Deposit shall be an
     expense of such Trust Fund. The Depositor shall deliver any additional
     Securities which were not delivered concurrently with the deposit of
     additional Securities and which were represented by Contract Obligations
     within 10 calendar days after such deposit of additional Securities (the
     "Additional Securities Delivery Period"). If a contract to buy such
     Securities between the Depositor and seller is terminated by the seller
     thereof for any reason beyond the control of the Depositor or if for any
     other reason such Securities are not delivered to a Trust by the end of the
     Additional Securities Delivery Period for such deposit, the Trustee shall
     immediately draw on the Letter of Credit, if any, in amounts sufficient to
     settle such contract, apply the monies in accordance with Section 2.01(d),
     and the Depositor shall forthwith take the remedial action specified in
     Section 3.10. If the Depositor does not take the action specified in
     Section 3.10 within 10 calendar days of the end of the Additional
     Securities Delivery Period, the Trustee shall forthwith take the action
     specified in Section 3.10. If the Depositor has acted as broker in
     connection with any purchase of Securities made on behalf of a Trust, which
     it is hereby authorized to do, it shall be entitled to reimbursement in
     accordance with applicable law and regulations. The Trustee shall have no
     liability for any loss or depreciation resulting from any acquisition of
     Securities pursuant to this Section (other than to confirm the identity and
     amount of Securities delivered to it pursuant to contracts deposited or
     entered into by the Depositor) and shall have no responsibility for the
     composition of a Trust portfolio.

          (2) Additional Securities (or Contract Securities therefor) may, at
     the Depositor's discretion, be deposited or purchased in round lots. If the
     amount of the deposit is insufficient to acquire round lots of each
     Security to be acquired, the additional Securities shall be deposited or
     purchased in accordance with the instructions of the Depositor or its
     designee.

          (3) If at the time of a deposit of additional Securities, Securities
     of an issue deposited on the Initial Date of Deposit (or of an issue of
     Replacement Securities acquired to replace an issue deposited on the
     Initial Date of Deposit) are unavailable, cannot be purchased at reasonable
     prices or their purchase is prohibited or restricted by applicable law,
     regulation or policies, the Depositor may (i) deposit, or purchase on
     behalf of each Trust or designate an agent to purchase on behalf of each
     Trust in respect of cash deposited therein for such purpose, in lieu
     thereof, another issue of Securities or Replacement Securities or (ii)
     deposit cash or a letter of credit in an amount equal to the valuation of
     the issue of Securities whose acquisition is not feasible and enter into
     contracts, or designate an agent to enter into contracts, on behalf of a
     Trust to acquire such Securities of such issue when they become available.

          (4) In connection with and at the time of any deposit of additional
     Securities pursuant to this Section 2.01(b), the Depositor shall exactly
     replicate Cash (as defined below) received or receivable by the Trust as of
     the date of such deposit. For purposes of this paragraph, "Cash" means, as
     to the Capital Account, cash or other property (other than Securities) on
     hand in the Capital Account or receivable and to be credited to the Capital
     Account as of the date of the deposit (other than amounts to be distributed
     solely to persons other than holders of Units created by the deposit) and,
     as to the Income Account, cash or other property (other than Securities)
     received by the Trust in respect of a record date for a payment on a
     Security which has occurred or will occur before the Trusts will be the
     holder of record of a Security, reduced by (i) the amount of any cash or
     other property received or receivable on any Security allocable (in
     accordance with the Trustee's calculations of distributions from the Income
     Account pursuant to Section 3.05) to a distribution made or to be made in
     respect of a Record Date occurring prior to the deposit and (ii) unpaid
     fees and expenses allocable to the period prior to the deposit. Such
     replication will be made on the basis of a fraction, the numerator of which
     is the number of Units created by the deposit and the denominator of which
     is the number of Units which are outstanding immediately prior to the
     deposit. Cash represented by a foreign currency shall be replicated in such
     currency or, if the Trustee has entered into a contract for the conversion
     thereof, in U.S. dollars in an amount replicating the dollars to be
     received on such conversion.

          (z) If a Trust has elected to be treated as a "regulated investment
company" as defined in the Internal Revenue Code, the following shall be added
as subsection (f) to Section 3.04:

          (f) Notwithstanding the foregoing, if a Trust has elected to be
treated as a "regulated investment company" as defined in the Internal Revenue
Code of 1986, as amended, the Trustee may make such additional distributions to
Unitholders as shall be determined by the Depositor or such agent as the
Depositor shall designate to be necessary or desirable to maintain the status of
each Trust as a Regulated Investment Company or to avoid imposition of any
income or excise taxes on undistributed income of the Trust. The Trustee shall
be authorized to rely conclusively upon the direction, and shall have no duty to
make any additional distributions from the Trusts in the absence of such
direction. The Trustee shall have no liability for any tax or other liability
incurred by reason of action or inaction resulting from such direction. The fees
of such agent designated by the Depositor shall be an expense of the Trusts
reimbursable to the Trustee in accordance with Section 8.05.

          (aa) If a Trust has elected to be treated as a "regulated investment
company" as defined in the Internal Revenue Code, the following replaces the
second paragraph of Section 3.08:

          In the event that an offer by the issuer of any of the Securities or
     any other party shall be made to issue new securities, or to exchange
     securities, for Trust Securities, the Trustee shall reject such offer.
     However, should any issuance, exchange or substitution be effected
     notwithstanding such rejection or without an initial offer, any securities,
     cash and/or property received shall be deposited hereunder and shall be
     promptly sold, if securities or property, by the Trustee; provided,
     however, if such securities are components of the applicable index, the
     Depositor may advise the Trustee to keep such securities. The cash received
     in such exchange and cash proceeds of any such sales shall, as the
     Depositor or its designee shall direct, be (1) reinvested into any
     Securities included in the applicable index or (2) distributed to
     Unitholders on the next Capital Distribution Date in the manner set forth
     in this Agreement regarding distributions from the Capital Account. Without
     limiting the generality of the foregoing, in determining whether such
     reinvestment is practicable, the Depositor may, but is not obligated to,
     specifically consider the ability of a Trust to reinvest such proceeds into
     round lots of a Security. Except as provided in Article VIII, the Trustee
     shall not be liable or responsible in any way for depreciation or loss
     incurred by reason of any such rejection or sale.

          (bb) If a Trust has elected to be treated as a "regulated investment
company" as defined in the Internal Revenues Code, and not withstanding anything
to the foregoing, section 3.06 shall be amended to read, in its entirety, as
follows:

          Section 3.06. Sale of Securities and Reinvestment. The Depositor by
     written notice may direct the Trustee to sell Securities at such price and
     time and in such manner as shall be deemed appropriate by the Depositor if
     the Depositor shall have determined that any one or more of the following
     conditions exist:

          (a) that there has been a default in the payment of principal of or
     interest on any outstanding debt obligations of the issuer of such
     Securities;

          (b) that the price of any such Security has declined to such an
     extent, as a result of adverse issuer credit factors, so that in the
     opinion of the Depositor the retention of such Securities would be
     detrimental to the interest of the Unitholders;

          (c) if a Trust has elected to be treated as a "regulated investment
     company" as defined in the Internal Revenue Code that such sale is
     necessary or advisable (i) to maintain the qualification of the Trust as a
     regulated investment company or (ii) to provide funds to make any
     distribution for a taxable year in order to avoid imposition of any income
     or excise taxes on undistributed income in the Trust;

          (d) that the Security has been removed from the applicable index; or

          (e) Depositor or its designee determines that such sale is
     appropriate.

          Upon receipt of such direction from the Depositor, the Trustee shall
     proceed to sell the specified Securities in such manner as the Depositor or
     its designee shall direct. The Depositor or its designee may enter into
     contracts on behalf of the Trust to reinvest the proceeds of the sale of
     any Security sold pursuant to this section, Section 5.02 or otherwise
     pursuant to this Agreement into any Security included in the applicable
     index. Without limiting the generality of the foregoing, in determining
     whether such reinvestment is practicable, the Depositor may, but is not
     obligated to, specifically consider the ability of the Trust to reinvest
     such proceeds into round lots of a Security. Contracts for sale or purchase
     of Securities shall be made by the Depositor on behalf of the Trust or by
     such agent as the Depositor shall designate. The Depositor or its designee
     shall provide the Trustee such information as the Trustee may require in
     order to settle the transactions. the Trustee shall not be liable or
     responsible in any way for depreciation or loss incurred by reason of any
     sale or purchase made pursuant to any such direction or by reason of the
     failure of the Depositor to give any such direction, and in the absence of
     such direction the Trustee shall have no duty to sell or purchase any
     Securities under this Section 3.06 and shall have no responsibility for the
     composition of each Trust portfolio. The Depositor shall not be liable for
     errors of judgment in directing or failing to direct the Trustee pursuant
     to this Section 3.06. This provision, however, shall not protect the
     Depositor against any liability for which it would otherwise be subject, by
     reason of willful misfeasance, bad faith or gross negligence in the
     performance of its duties or by reason of its reckless disregard of its
     obligations and duties hereunder.

          The Depositor or its designated agent shall make such reviews of each
     Trust portfolio as shall be necessary to maintain qualification of the
     Trust as a Regulated Investment Company and the Depositor shall be
     authorized to rely conclusively upon such reviews in directing sales
     pursuant to paragraph (c) of this section.

          (cc) If a Trust has elected to be treated as a "regulated investment
company" as defined in the Internal Revenue Code, the following paragraph shall
be added to Section 9.01:

          If the Trust involved seeks to consist of securities included in a
     securities index, and notwithstanding anything to the contrary herein, if
     at any time the index shall no longer be compiled, maintained or made
     available, the Depositor may (a) direct that the Trust created hereby
     continue to be operated hereunder utilizing the components of the index as
     existed on the last date on which the index components were available to a
     Trust or (b) direct the Trustee to terminate this Agreement and the Trusts
     created hereby and liquidate the Trusts in such manner as the Depositor
     shall direct.

          (dd) If a Trust has elected to be treated as a "regulated investment
company" as defined in the Internal Revenue Code, the first paragraph of Section
10.01 shall be replaced with the following paragraph:

          Section 10.01. Amendment and Waiver. This Agreement may be amended
     from time to time by the Depositor and the Trustee without the consent of
     any of the Unitholders (a) to cure any ambiguity or to correct or
     supplement any provisions contained herein which may be defective or
     inconsistent with any other provision contained herein; (b) to change any
     provision hereof as may be required by the Securities and Exchange
     Commission or any successor governmental agency exercising similar
     authority; (c) to make such amendments as may be necessary for each Trust
     to continue to qualify as a regulated investment company for federal income
     tax purposes; or (d) to make such other provisions in regard to matters or
     questions arising hereunder as shall not adversely affect the interest of
     the Unitholders (as determined in good faith by the Depositor and the
     Trustee). This Agreement may also be amended from time to time by the
     Depositor and the Trustee (or the performance of any of the provisions of
     this Agreement may be waived) with the consent of holders of Units
     representing 66-3/3% of the Units at the time outstanding under the Trust
     Agreement of the individual Trust Fund or Trust Funds affected for the
     purpose of adding any provisions of this Agreement or of materially
     modifying in any manner the rights of the holders of Units of such Trust
     Fund or Trust Funds; provided, however, that in no event may any amendment
     be made which would (a) alter the rights to the Unitholders as against each
     other, (b) provide the Trustee with the power to engage in business or
     investment activities other than as specifically provided in this Agreement
     or (c) adversely affect the characterization of a Trust as a regulated
     investment company for federal income tax purposes; provided, further, that
     the consent of 100% of the Unitholders of any individual Trust Fund is
     required to amend this Agreement (a) to reduce the aforesaid percentage of
     Units the holders of which are required to consent to certain amendments
     and (b) to reduce the interest in such Trust Fund represented by any Units
     of such Trust Fund.

          (ee) If a Trust has elected to be treated as a "regulated investment
company" as defined in the Internal Revenue Code, the second paragraph of
Section 3.04(b) shall have the following added to the end of the paragraph:

          Notwithstanding anything to the contrary contained in this paragraph,
     the Depositor or its designee may, but is not obligated to, direct the
     investment of any amounts held in the Capital Account that have not
     previously been used to pay for the redemption of Units tendered to a Trust
     Fund, into any Securities included in the applicable index.

          (ff) If a Trust has elected to be treated as a "regulated investment
company" as defined in the Internal Revenue Code, paragraphs (a) and (b) of
Section 3.10 shall be amended as follows:

          (a)  The New Securities shall be a component of the applicable index.

          (b)  The Depositor shall furnish a notice to the Trustee (which may be
     part of the Failed Contract Notice) in respect to the New Security
     purchased or to be purchased that shall (i) identify the New Securities,
     (ii) state that the contract to purchase, if any, entered into by the
     Depositor is satisfactory in form and substance and (iii) state that the
     foregoing conditions of clause (a) have been satisfied with respect to the
     New Securities.

     Paragraph (c) of Section 3.10 shall be deleted.

          (gg) For each Trust that does not elect to be treated as a "regulated
investment company" under the Internal Revenue Code, Section 2.01(b)(5) is
hereby amended by adding the following at the conclusion thereof:

          Cash represented by a foreign currency shall be replicated in such
     currency or, if the Trustee has entered into a contract for the conversion
     thereof, in U.S. dollars in an amount replicating the dollars to be
     received on such conversion.

                                 -3-
<PAGE>

          In Witness Whereof, John Nuveen & Co. Incorporated, has caused this
Trust Indenture and Agreement for Nuveen Unit Trusts, Series 91 to be executed
by its President, one of its Vice Presidents or one of its Assistant Vice
Presidents and its corporate seal to be hereto affixed and attested by its
Secretary or its Assistant Secretary and The Chase Manhattan Bank has caused
this Trust Indenture and Agreement to be executed by one of its Vice Presidents
or Second Vice Presidents and its corporate seal to be hereto affixed and
attested to by one of its Assistant Treasurers; all as of the day, month and
year first above written.

                                       John Nuveen & Co. Incorporated,
                                                      Depositor


                                       By /s/ Thomas C. Muntz
                                         ----------------------------
                                              Authorized Officer


(Seal)

Attest:
By /s/ Nicolas Dalmaso
  -------------------------
     Assistant Secretary

                                       The Chase Manhattan Bank, Trustee


                                       By /s/ James P. Donovan
                                         ----------------------------
                                           Assistant Vice President


(Seal)

Attest:

By /s/ Robert E. Lisk
  --------------------------
      Assistant Treasurer

                                      -4-
<PAGE>

                Schedule A to the Trust Indenture and Agreement

                        Securities Initially Deposited

                                      in

                      Nuveen Unit Trusts, SERIES 91


    (Note:  Incorporated herein and made a part hereof is the "Schedule of
            Investments" as set forth for the Trust(s) in the Prospectus.)

                                      -5-

<PAGE>

                                                                     Exhibit 3.1


                                  May 15, 2000


John Nuveen & Co. Incorporated
333 West Wacker Drive
Chicago, Illinois  60606


         Re:                Nuveen Unit Trusts, Series 91
                            -----------------------------


Gentlemen:


         We have served as counsel for you, as Depositor of Nuveen Unit Trusts,
Series 88 (hereinafter referred to as the "Fund"), in connection with the
issuance under the Trust Indenture and Agreement dated the date hereof between
John Nuveen & Co. Incorporated, as Depositor, and The Chase Manhattan Bank, as
Trustee, of Units of fractional undivided interest in the one or more Trusts of
said Fund (hereinafter referred to as the "Units").

     In connection therewith, we have examined such pertinent records and
documents and matters of law as we have deemed necessary in order to enable us
to express the opinions hereinafter set forth.

     Based upon the foregoing, we are of the opinion that:

     1.  The execution and delivery of the Trust Indenture and Agreement and the
 establishment of book entry positions and the execution and issuance of
 certificates evidencing the Units in the Trust(s) of the Fund have been duly
 authorized; and

     2.  The book entry positions and certificates evidencing the Units in the
 Trust(s) of the Fund when duly established or duly executed and delivered by
 the Depositor and the Trustee in accordance with the aforementioned Trust
 Indenture and Agreement, will constitute valid and binding obligations of such
 Trust(s) and the Depositor in accordance with the terms thereof.

     We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement (File No. 333-36520) relating to the Units referred to
above and to the use of our name and to the reference to our firm in said
Registration Statement and in the related Prospectus.

                                     Respectfully submitted,

                                     /s/ Chapman and Cutler

                                     Chapman and Cutler


<PAGE>

                                                                     Exhibit 3.2




                                 May 15, 2000



John Nuveen & Co. Incorporated
333 West Wacker Drive
Chicago, Illinois  60606


The Chase Manhattan Bank
Nuveen Administration Department
4 New York Plaza, Third Floor
New York, New York  10004-2413


    Re:  Nuveen Unit Trusts, Series 91
         ----------------------------------------------------------------------

Gentlemen:

     We have acted as counsel for John Nuveen & Co. Incorporated, as Sponsor and
Depositor of Nuveen Unit Trusts, Series 91 (the "Fund"), in connection with the
issuance of Units of fractional undivided interest in the Trust(s), under a
Trust Indenture and Agreement dated May 15, 2000 (the "Indenture") between
John Nuveen & Co. Incorporated, as Depositor, and The Chase Manhattan Bank, as
Trustee and Evaluator.

     In this connection, we have examined the Registration Statement, the form
of Prospectus proposed to be filed with the Securities and Exchange Commission,
the Indenture and such other instruments and documents we have deemed pertinent.
The opinions expressed herein assume that the Trust(s) will be administered, and
investments by the Trust(s) from proceeds of subsequent deposits, if any, will
be made, in accordance with the terms of the Indenture. The assets of each
Trust will consist of a portfolio of equity securities (the "Securities") as set
forth in the Prospectus. For purposes of the following discussion and opinion,
it is assumed that each Security is equity for federal income tax purposes.

     Based upon the foregoing and upon an investigation of such matters of law
as we consider to be applicable, we are of the opinion that, under existing
federal income tax law:

       I. Each Trust is not an association taxable as a corporation for Federal
income tax purposes but will be governed by the provisions of subchapter J
(relating to Trusts) of Chapter 1, Internal Revenue Code of 1986 (the "Code");
each Unitholder will be treated as the owner of a pro rata portion of each of
the assets of the Trust(s), in the proportion that the

<PAGE>

number of Units held by him bears to the total number of Units outstanding;
under Subpart E, Subchapter J of Chapter 1 of the Code, income of the Trust(s)
will be treated as income of the Unitholders in the proportion described above;
and an item of Trust income will have the same character in the hands of a
Unitholder as it would have in the hands of the Trustee. Each Unitholder will be
considered to have received his pro rata share of income derived from each Trust
asset when such income is considered to be received by the Trust(s). A
Unitholder's pro rata portion of distributions of cash or property by a
corporation with respect to a Security ("dividends" as defined by Section 316 of
the Code), is taxable as ordinary income to the extent of such corporation's
current and accumulated "earnings and profits." A Unitholder's pro rata portion
of dividends paid on such Security which exceeds such current and accumulated
earnings and profits will first reduce a Unitholder's tax basis in such Equity
Security, and to the extent that such dividends exceed a Unitholder's tax basis
in such Security, shall be treated as gain from the sale or exchange of
property.

       II.  The price a Unitholder pays for his Units generally including sales
charges, is allocated among his pro rata portion of each Security held by the
Trust(s) (in proportion to the fair market values thereof on the valuation date
closest to the date the Unitholder purchases his Units), in order to determine
his tax basis for his pro rata portion of each Security held by a Trust.

       III.  Gain or loss will be recognized to a Unitholder (subject to various
nonrecognition provisions under the Code) upon redemption or sale of his Units,
except to the extent an in kind distribution of securities is received by such
Unitholder from the Trust(s) as discussed below. Such gain or loss is measured
by comparing the proceeds of such redemption or sale with the adjusted basis of
his Units. Before adjustment, such basis would normally be cost if the
Unitholder had acquired his Units by purchase. Such basis will be reduced, but
not below zero, by the Unitholder's pro rata portion of dividends with respect
to each Security which is not taxable as ordinary income.

      IV.  If the Trustee disposes of a Trust asset (whether by sale, taxable
exchange, liquidation, redemption, payment on maturity or otherwise) gain or
loss will be recognized to the Unitholder (subject to various nonrecognition
provisions under the Code) and the amount thereof will be measured by comparing
the Unitholder's aliquot share of the total proceeds from the transaction with
his basis for his fractional interest in the asset disposed of. Such basis is
ascertained by apportioning the tax basis for his Units (as of the date on which
his Units were acquired) among each of the Trust's assets (as of the date on
which his Units were acquired) ratably according to their values as of the
valuation date nearest the date on which he purchased such Units. A Unitholder's
basis in his Units and of his fractional interest in each Trust asset must be
reduced, but not below zero, by the Unitholder's pro rata portion of dividends
with respect to each Security which are not taxable as ordinary income.

<PAGE>

     V. Under the Indenture, under certain circumstances, a Unitholder tendering
Units for redemption may request an in kind distribution of Securities upon the
redemption of Units or upon the termination of the Trust(s). As previously
discussed, prior to the redemption of Units or the termination of the Trust(s),
a Unitholder is considered as owning a pro rata portion of each of a Trust's
assets. The receipt of an in kind distribution will result in a Unitholder
receiving an undivided interest in whole shares of stock and possibly cash. The
potential federal income tax consequences which may occur under an in kind
distribution with respect to each Security owned by the Trust(s) will depend
upon whether or not a Unitholder receives cash in addition to Securities. A
"Security" for this purpose is a particular class of stock issued by a
particular corporation. A Unitholder will not recognize gain or loss if a
Unitholder only receives Securities in exchange for his or her pro rata portion
of the Securities held by the Trust(s). However, if a Unitholder also receives
cash in exchange for a fractional share of a Security held by the Trust(s), such
Unitholder will generally recognize gain or loss based upon the difference
between the amount of cash received by the Unitholder and his tax basis in such
fractional share of a Security held by the Trust(s). The total amount of taxable
gains (or losses) recognized upon such redemption will generally equal the sum
of the gain (or loss) recognized under the rules described above by the
redeeming Unitholder with respect to each Security owned by the Trust(s).

     A domestic corporation owning Units in the Trust(s) may be eligible for the
70% dividends received deduction pursuant to Section 243(a) of the Code with
respect to such Unitholder's pro rata portion of dividends received by a Trust
(to the extent such dividends are taxable as ordinary income, as discussed
above, and are attributable to domestic corporations), subject to the
limitations imposed by Sections 246 and 246A of the Code.

     To the extent dividends received by the Trust(s) are attributable to
foreign corporations, a corporation that owns Units will not be entitled to the
dividends received deduction with respect to its pro rata portion of such
dividends since the dividends received deduction is generally available only
with respect to dividends paid by domestic corporations.

     Section 67 of the Code provides that certain miscellaneous itemized
deductions, such as investment expenses, tax return preparation fees and
employee business expenses will be deductible by an individual only to the
extent they exceed 2% of such individual's adjusted gross income.  Unitholders
may be required to treat some or all of the expenses of the Trust(s) as
miscellaneous itemized deductions subject to this limitation.

     A Unitholder will recognize taxable gain (or loss) when all or part of the
pro rata interest in a Security is either sold by the Trust(s) or redeemed or
when a Unitholder disposes of his Units in a taxable transaction, in each case
for an amount greater (or less) than his tax basis therefor, subject to various
non-recognition provisions of the Code.

     It should be noted that payments to the Trust(s) of dividends on Securities
that are attributable to foreign corporations may be subject to foreign
withholding taxes and Unitholders should consult their tax advisers regarding
the potential tax consequences relating to the payment of any such withholding
taxes by the Trust(s). Any dividends withheld as a result thereof will
nevertheless be treated as income to the Unitholders. Because under the grantor
trust rules, an investor is deemed to have paid directly his share of foreign
taxes that have been paid or accrued, if any, an investor may be entitled to a
foreign tax credit or deduction for United States tax purposes with respect to
such taxes. A required holding period is imposed for such credits.

<PAGE>

     Any gain or loss recognized on a sale or exchange will, under current law,
generally be capital gain or loss.

     The scope of this opinion is expressly limited to the matters set forth
herein, and, except as expressly set forth above, we express no opinion with
respect to any other taxes, including foreign, state or local taxes or
collateral tax consequences with respect to the purchase, ownership and
disposition of Units.


     We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement (File No. 333-36520) relating to the Units referred to
above and to the use of our name and to the reference to our firm in said
Registration Statement and in the related Prospectus.

                                     Very truly yours,

                                     /s/ Chapman and Cutler

                                     Chapman and Cutler


<PAGE>

                   [Letterhead of Carter, Ledyard & Milburn]

                                                                    Exhibit 3.3

                                  May 15, 2000



The Chase Manhattan Bank,
 as Trustee of
Nuveen Unit Trusts, Series 91
New York, New York 10004

Attention: Mr. Steven B. Wolinsky
           Senior Vice President

         Re:     Nuveen Unit Trusts, Series 91
                 -----------------------------

Dear Sirs:

     We are acting as special counsel with respect to New York tax matters for
Nuveen Unit Trusts, Series 91, (the "Trust Fund"), which will be established
under a Standard Terms and Conditions of Trust for Nuveen Unit Trust Series 4
and certain subsequent Series dated May 29, 1997 and a related Trust Indenture
and Agreement dated today's date (such Standard Terms and Conditions of Trust
and related Trust Indenture and Agreement are referred to collectively as the
"Indenture"), each between John Nuveen & Co. Incorporated, as Depositor (the
"Depositor"), and The Chase Manhattan Bank, as Trustee (the "Trustee"). Pursuant
to the terms of the Indenture, units of fractional undivided interest in the
Trust Fund will be issued (the "Units"), which Units may, in accordance with the
Indenture, be represented by a certificate or certificates (the "Certificates").

    We have examined and are familiar with originals or certified copies, or
copies otherwise identified to our satisfaction, of such documents as we have
deemed necessary or appropriate for the purpose of this opinion. In giving this
opinion, we have relied upon the two opinions, each dated today and addressed to
the Trustee, of Chapman and Cutler, counsel for the Depositor, with respect to
the matters of law set forth therein.

     Based upon the foregoing, we are of the opinion that:
<PAGE>

          1.  The Trust Fund will not constitute an association taxable as a
     corporation under New York law, and accordingly will not be subject to the
     New York State franchise tax or the New York City general corporation tax.

          2.  Under the income tax laws of the State and City of New York, the
     income of the Trust Fund will be considered the income of the holders of
     the Units.

          3.  By reason of the exemption contained in paragraph (a) of
     Subdivision 8 of Section 270 of the New York Tax Law, no New York State
     stock transfer tax will be payable in respect of any transfer of the
     Certificates.

     We consent to the filing of this opinion as an exhibit to the Registration
Statement (No. 333-36520) filed with the Securities and Exchange Commission with
respect to the registration of the sale of the Units and to the references to
our name under the captions "Tax Status" and "Legal Opinion" in such
Registration Statement and the preliminary prospectus included therein.

                                       Very truly yours,

                                       CARTER, LEDYARD & MILBURN

                                      -2-

<PAGE>

                   [Letterhead of Carter, Ledyard & Milburn]

                                                                     Exhibit 3.4

                                  May 15, 2000

The Chase Manhattan Bank,
as Trustee of
Nuveen Unit Trusts, Series 91
4 New York Plaza, 3rd Floor
New York, New York 10004

Attention: Mr. Steven B. Wolinsky
           Senior Vice President

       Re:       Nuveen Unit Trusts, Series 91
                 -----------------------------

Dear Sirs:

     We are acting as counsel for The Chase Manhattan Bank ("Chase") in
connection with the execution and delivery of a Standard Terms and Conditions of
Trust for Nuveen Unit Trust Series 4 and certain subsequent Series dated May 29,
1997 and a related Trust Indenture and Agreement dated today's date (such
Standard Terms and Conditions of Trust and related Trust Indenture and Agreement
are collectively referred to as the "Indenture"), each between John Nuveen & Co.
Incorporated, as Depositor (the "Depositor"), and Chase, as Trustee (the
"Trustee"), establishing the Nuveen Unit Trusts, Series 91 (the "Trust Fund"),
and the confirmation by Chase, as Trustee under the Indenture, that it has
caused to be credited to the Depositor's account at The Depository Trust Company
a number of units constituting the entire interest in the Trust Fund (such
aggregate units being herein called "Units"), each of which represents an
undivided interest in such Trust Fund, which consists of common stocks
(including confirmations of contracts for the purchase of certain stock not yet
delivered and cash, cash equivalents or an irrevocable letter of credit in the
amount required for such purchase upon the receipt of such stock), such stocks
being defined in the Indenture as Securities and referenced in the schedules to
the Indenture.
<PAGE>

     We have examined the Indenture, the Closing Memorandum executed and
delivered today by the Depositor and the Trustee (the "Closing Memorandum"), the
form of certificate for the Units included in the Indenture and a specimen of
the certificates to be issued thereunder (the "Certificates") and such other
documents as we have deemed necessary in order to render this opinion. Based on
the foregoing, we are of the opinion that:

          1.  Chase is a duly organized and existing corporation having the
     powers of a trust company under the laws of the State of New York.

          2.  The Indenture has been duly executed and delivered by Chase and,
     assuming due execution and delivery by the Depositor, constitutes the valid
     and legally binding obligation of Chase.

          3.  The Certificates are in proper form for execution and delivery by
     Chase, as Trustee.

          4.  Chase, as Trustee, has registered on the registration books of
     the Trust Fund the ownership of the Units by The Depository Trust Company,
     where it has caused the Units to be credited to the account of the
     Depositor. Upon receipt of confirmation of the effectiveness of the
     registration statement for the sale of the Units filed with the Securities
     and Exchange Commission under the Securities Act of 1933, the Trustee may
     cause the Units to be transferred on the registration books of the Trust
     Fund to such other names, and in such denominations, as the Depositor may
     order, and may deliver Certificates evidencing such ownership as provided
     in the Closing Memorandum.

     In rendering the foregoing opinion, we have not considered, among other
things, whether the Securities have been duly authorized and delivered.

                              Very truly yours,

                              CARTER, LEDYARD & MILBURN

<PAGE>

                                     [On Letterhead of The Chase Manhattan Bank]


                                                                     Exhibit 4.2



                                  May 15, 2000



John Nuveen & Co. Incorporated
333 West Wacker Drive
Chicago, Illinois  60606


     Re:          Nuveen Unit Trusts--Series 91
                  ----------------------------------------
Dear Sirs:

     The Chase Manhattan Bank is acting as Evaluator for the series of Nuveen
Unit Trust set forth above (the "Trust"). We enclose a list of the Securities to
be deposited in the Trust on the date hereof. The prices indicated therein
reflect our evaluation of such Securities as of close of business on May
12, 2000 in accordance with the valuation method set forth in the Standard Terms
and Conditions of Trust for Nuveen Unit Trust Series 4 and subsequent. We
consent to the reference to The Chase Manhattan Bank as the party performing the
evaluations of the Trust Securities in the Registration Statement (No.
333-36520) filed with the Securities and Exchange Commission with respect to the
registration of the sale of the Trust Units and to the filing of this consent as
an exhibit thereto.

                             Very truly yours,

                                     /s/ Jennifer Polintan

                                     Assistant Treasurer

<PAGE>

                                                                     Exhibit 4.4




                   Consent of Independent Public Accountants

     As independent public accountants, we hereby consent to the use of our
report and to all references to our Firm included in or made a part of this
Registration Statement.






                                      Arthur Andersen LLP


Chicago, Illinois

May 15, 2000



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