<TABLE> <S> <C>

<PAGE>
 
<ARTICLE> 9
<LEGEND>
This schedule contains summary financial information extracted from the
consolidated balance sheets of Summit Bancshares, Inc., as of March 31, 1999,
and the related statements of income, changes in shareholders' equity and cash
flows for the period ending March 31, 1999 and is qualified in its entirety by
reference to such financial statements.
</LEGEND>
<MULTIPLIER> 1,000 
       
<S>                             <C>
<PERIOD-TYPE>                   3-MOS
<FISCAL-YEAR-END>                          DEC-31-1999
<PERIOD-START>                             JAN-01-1999
<PERIOD-END>                               MAR-31-1999
<CASH>                                          23,371
<INT-BEARING-DEPOSITS>                               0
<FED-FUNDS-SOLD>                                16,800
<TRADING-ASSETS>                                     0
<INVESTMENTS-HELD-FOR-SALE>                    117,953
<INVESTMENTS-CARRYING>                         148,297
<INVESTMENTS-MARKET>                           148,377
<LOANS>                                        318,795
<ALLOWANCE>                                      4,749
<TOTAL-ASSETS>                                 521,258
<DEPOSITS>                                     455,383
<SHORT-TERM>                                    16,533
<LIABILITIES-OTHER>                              2,770
<LONG-TERM>                                          0
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                         8,133
<OTHER-SE>                                      38,439
<TOTAL-LIABILITIES-AND-EQUITY>                 521,258
<INTEREST-LOAN>                                  7,009
<INTEREST-INVEST>                                2,082
<INTEREST-OTHER>                                   303
<INTEREST-TOTAL>                                 9,394
<INTEREST-DEPOSIT>                               3,094
<INTEREST-EXPENSE>                               3,254
<INTEREST-INCOME-NET>                            6,140
<LOAN-LOSSES>                                      220
<SECURITIES-GAINS>                                   0
<EXPENSE-OTHER>                                  3,738
<INCOME-PRETAX>                                  3,213
<INCOME-PRE-EXTRAORDINARY>                       2,096
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                     2,096
<EPS-PRIMARY>                                      .33
<EPS-DILUTED>                                      .31
<YIELD-ACTUAL>                                    5.16
<LOANS-NON>                                      4,207
<LOANS-PAST>                                         0
<LOANS-TROUBLED>                                     0
<LOANS-PROBLEM>                                  9,597
<ALLOWANCE-OPEN>                                 4,724
<CHARGE-OFFS>                                      234
<RECOVERIES>                                        39
<ALLOWANCE-CLOSE>                                4,749
<ALLOWANCE-DOMESTIC>                             4,749
<ALLOWANCE-FOREIGN>                                  0
<ALLOWANCE-UNALLOCATED>                              0
        

</TABLE>