<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE
STATEMENT OF INCOME FOR THE SIX MONTHS ENDED JUNE 30, 1997 AND THE BALANCE SHEET
AS OF JUNE 30, 1997 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH
FINANCIAL STATEMENTS.
</LEGEND>
<MULTIPLIER> 1,000
       
                             
<PERIOD-TYPE>                   6-MOS
<FISCAL-YEAR-END>                          DEC-31-1997
<PERIOD-START>                             JAN-01-1997
<PERIOD-END>                               JUN-30-1997
<CASH>                                           6,097
<SECURITIES>                                         0
<RECEIVABLES>                                  156,147
<ALLOWANCES>                                     8,317
<INVENTORY>                                      2,123
<CURRENT-ASSETS>                               181,974
<PP&E>                                       1,585,241
<DEPRECIATION>                                 801,680
<TOTAL-ASSETS>                                 974,108
<CURRENT-LIABILITIES>                          245,168
<BONDS>                                        227,736
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                       191,968
<OTHER-SE>                                     107,255
<TOTAL-LIABILITY-AND-EQUITY>                   974,108
<SALES>                                              0
<TOTAL-REVENUES>                               309,027
<CGS>                                                0
<TOTAL-COSTS>                                  250,762
<OTHER-EXPENSES>                                     0
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                               9,520
<INCOME-PRETAX>                                 47,512
<INCOME-TAX>                                    18,963
<INCOME-CONTINUING>                             28,549
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                    28,549
<EPS-PRIMARY>                                        0
<EPS-DILUTED>                                        0