<ARTICLE> 5 <MULTIPLIER> 1,000 <PERIOD-TYPE> 6-MOS <FISCAL-YEAR-END> DEC-31-1997 <PERIOD-START> JAN-01-1997 <PERIOD-END> JUN-30-1997 <CASH> 18,800 <SECURITIES> 0 <RECEIVABLES> 144,600 <ALLOWANCES> 13,600 <INVENTORY> 0 <CURRENT-ASSETS> 175,900 <PP&E> 1,215,600 <DEPRECIATION> 413,800 <TOTAL-ASSETS> 1,348,000 <CURRENT-LIABILITIES> 436,100 <BONDS> 64,300 <PREFERRED-MANDATORY> 0 <PREFERRED> 0 <COMMON> 1,000 <OTHER-SE> 749,800 <TOTAL-LIABILITY-AND-EQUITY> 1,348,000 <SALES> 0 <TOTAL-REVENUES> 546,900 <CGS> 0 <TOTAL-COSTS> 401,000 <OTHER-EXPENSES> 0 <LOSS-PROVISION> 0 <INTEREST-EXPENSE> 14,400 <INCOME-PRETAX> 76,900 <INCOME-TAX> 27,800 <INCOME-CONTINUING> 49,100 <DISCONTINUED> 0 <EXTRAORDINARY> 0 <CHANGES> 0 <NET-INCOME> 49,100 <EPS-PRIMARY> .51 <EPS-DILUTED> .51