WARNING: THE EDGAR SYSTEM ENCOUNTERED ERROR(S) WHILE PROCESSING THIS SCHEDULE.
<TABLE> <S> <C>
<ARTICLE> 6
<RESTATED>
<CIK> 0000860953
<NAME> NUVEEN TAX-FREE UNIT TRUST
<SERIES> Series 622
<NAME> CONNECTICUT TRADITIONAL TRUST
<NUMBER> 246
<MULTIPLIER> 1
<CURRENCY> U.S. DOLLARS
<FISCAL-YEAR-END> JUL-31-2000
<PERIOD-START> AUG-01-1999
<PERIOD-END> JUL-31-2000
<PERIOD-TYPE> YEAR
<EXCHANGE-RATE> 1
<INVESTMENTS-AT-COST> 2,147,712
<INVESTMENTS-AT-VALUE> 2,422,935
<RECEIVABLES> 46,083
<ASSETS-OTHER> 0
<OTHER-ITEMS-ASSETS> 0
<TOTAL-ASSETS> 2,469,018
<PAYABLE-FOR-SECURITIES> 0
<SENIOR-LONG-TERM-DEBT> 0
<OTHER-ITEMS-LIABILITIES> 41,841
<TOTAL-LIABILITIES> 41,841
<SENIOR-EQUITY> 0
<PAID-IN-CAPITAL-COMMON> 0
<SHARES-COMMON-STOCK> 30,373
<SHARES-COMMON-PRIOR> 33,496
<ACCUMULATED-NII-CURRENT> 26,956
<OVERDISTRIBUTION-NII> 0
<ACCUMULATED-NET-GAINS> 131,423
<OVERDISTRIBUTION-GAINS> 0
<ACCUM-APPREC-OR-DEPREC> 275,223
<NET-ASSETS> 2,427,177
<DIVIDEND-INCOME> 0
<INTEREST-INCOME> 156,510
<OTHER-INCOME> 0
<EXPENSES-NET> 4,282
<NET-INVESTMENT-INCOME> 152,228
<REALIZED-GAINS-CURRENT> -11,141
<APPREC-INCREASE-CURRENT> -45,568
<NET-CHANGE-FROM-OPS> 95,519
<EQUALIZATION> 0
<DISTRIBUTIONS-OF-INCOME> 186,032
<DISTRIBUTIONS-OF-GAINS> 874,566
<DISTRIBUTIONS-OTHER> 0
<NUMBER-OF-SHARES-SOLD> 50,000
<NUMBER-OF-SHARES-REDEEMED> 19,627
<SHARES-REINVESTED> 0
<NET-CHANGE-IN-ASSETS> -1,214,947
<ACCUMULATED-NII-PRIOR> 60,761
<ACCUMULATED-GAINS-PRIOR> 142,564
<OVERDISTRIB-NII-PRIOR> 0
<OVERDIST-NET-GAINS-PRIOR> 0
<GROSS-ADVISORY-FEES> 0
<INTEREST-EXPENSE> 0
<GROSS-EXPENSE> 0
<AVERAGE-NET-ASSETS> 0
<PER-SHARE-NAV-BEGIN> 0
<PER-SHARE-NII> 0
<PER-SHARE-GAIN-APPREC> 0
<PER-SHARE-DIVIDEND> 0
<PER-SHARE-DISTRIBUTIONS> 0
<RETURNS-OF-CAPITAL> 0
<PER-SHARE-NAV-END> 0
<EXPENSE-RATIO> 0
[AVG-DEBT-OUTSTANDING] 0
[AVG-DEBT-PER-SHARE] 0
</TABLE>
