<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM FORM 10-Q AS
OF JUNE 30, 1997 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH
FINANCIAL STATEMENTS
</LEGEND>
<MULTIPLIER> 1,000
       
                                                  
<PERIOD-TYPE>                   3-MOS                   6-MOS
<FISCAL-YEAR-END>                          DEC-31-1997             DEC-31-1997
<PERIOD-START>                             APR-01-1997             JAN-01-1997
<PERIOD-END>                               JUN-30-1997             JUN-30-1997
<CASH>                                          30,200                  30,200
<SECURITIES>                                         0                       0 
<RECEIVABLES>                                  142,747<F1>             142,747<F1>
<ALLOWANCES>                                         0                       0 
<INVENTORY>                                          0                       0 
<CURRENT-ASSETS>                               230,483                 230,483 
<PP&E>                                         677,641                 677,641 
<DEPRECIATION>                                 172,682                 172,682 
<TOTAL-ASSETS>                               1,134,459               1,134,459 
<CURRENT-LIABILITIES>                          192,913                 192,913 
<BONDS>                                        350,000                 350,000 
<PREFERRED-MANDATORY>                                0                       0 
<PREFERRED>                                          0                       0 
<COMMON>                                           783                     783 
<OTHER-SE>                                     482,330                 482,330 
<TOTAL-LIABILITY-AND-EQUITY>                 1,134,459               1,134,459 
<SALES>                                              0                       0 
<TOTAL-REVENUES>                               338,393                 653,043
<CGS>                                                0                       0
<TOTAL-COSTS>                                  199,535                 383,073
<OTHER-EXPENSES>                                96,247                 186,456
<LOSS-PROVISION>                                     0                       0
<INTEREST-EXPENSE>                               6,958                  13,688
<INCOME-PRETAX>                                 35,654                  69,826
<INCOME-TAX>                                    14,262                  27,931
<INCOME-CONTINUING>                             21,392                  41,895
<DISCONTINUED>                                       0                       0
<EXTRAORDINARY>                                      0                       0
<CHANGES>                                            0                       0
<NET-INCOME>                                    21,392                  41,895
<EPS-PRIMARY>                                      .25                     .49
<EPS-DILUTED>                                      .25                     .49
<FN>
<F1>Trade Accounts Receivable, less Allowance for Doubtful Accounts.
</FN>