<ARTICLE> 5
<CIK> 0000006769
<NAME> ART.5 FDS FOR 1997 THIRD QUARTER 10-Q
<MULTIPLIER> 1,000
<CURRENCY> U.S.DOLLAR
       
                             
<PERIOD-TYPE>                   9-MOS
<FISCAL-YEAR-END>                          DEC-31-1997
<PERIOD-START>                             JAN-01-1997
<PERIOD-END>                               SEP-30-1997
<EXCHANGE-RATE>                                  1,000
<CASH>                                          25,596
<SECURITIES>                                         0
<RECEIVABLES>                                  220,820
<ALLOWANCES>                                         0
<INVENTORY>                                     30,191
<CURRENT-ASSETS>                               287,798
<PP&E>                                       5,937,101
<DEPRECIATION>                               2,554,317
<TOTAL-ASSETS>                               3,726,414
<CURRENT-LIABILITIES>                          282,851
<BONDS>                                      1,312,595
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                       114,522
<OTHER-SE>                                   1,501,539
<TOTAL-LIABILITY-AND-EQUITY>                 3,726,414
<SALES>                                        714,196
<TOTAL-REVENUES>                               857,417
<CGS>                                          596,352
<TOTAL-COSTS>                                  596,352
<OTHER-EXPENSES>                                26,790
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                              51,048
<INCOME-PRETAX>                                183,227
<INCOME-TAX>                                    73,819
<INCOME-CONTINUING>                            109,408
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                   109,408
<EPS-PRIMARY>                                     1.19
<EPS-DILUTED>                                     1.17