<ARTICLE> 5 <MULTIPLIER> 1,000 <PERIOD-TYPE> 6-MOS <FISCAL-YEAR-END> DEC-31-1999 <PERIOD-START> JAN-01-1998 <PERIOD-END> JUN-30-1999 <CASH> 25,144 <SECURITIES> 0 <RECEIVABLES> 281,536 <ALLOWANCES> 0 <INVENTORY> 0 <CURRENT-ASSETS> 339,501 <PP&E> 1,935,809 <DEPRECIATION> 1,214,935 <TOTAL-ASSETS> 1,089,275 <CURRENT-LIABILITIES> 400,543 <BONDS> 150,350 <PREFERRED-MANDATORY> 0 <PREFERRED> 0 <COMMON> 29,375 <OTHER-SE> 345,665 <TOTAL-LIABILITY-AND-EQUITY> 1,089,275 <SALES> 0 <TOTAL-REVENUES> 1,483,554 <CGS> 0 <TOTAL-COSTS> 1,447,524 <OTHER-EXPENSES> (33) <LOSS-PROVISION> 0 <INTEREST-EXPENSE> 5,751 <INCOME-PRETAX> 30,312 <INCOME-TAX> 12,579 <INCOME-CONTINUING> 17,733 <DISCONTINUED> 0 <EXTRAORDINARY> 0 <CHANGES> 0 <NET-INCOME> 17,733 <EPS-BASIC> .71 <EPS-DILUTED> .70