<ARTICLE> 5
<MULTIPLIER> 1,000
       
                                                                       
<PERIOD-TYPE>                   9-MOS                   6-MOS                   3-MOS
<FISCAL-YEAR-END>                          DEC-31-1997             DEC-31-1997             DEC-31-1997
<PERIOD-START>                             JAN-01-1997             JAN-01-1997             JAN-01-1997
<PERIOD-END>                               SEP-30-1997             JUN-30-1997             MAR-31-1997
<CASH>                                           5,700                   9,200                  18,200
<SECURITIES>                                         0                       0                       0
<RECEIVABLES>                                  355,300                 346,100                 315,200
<ALLOWANCES>                                    13,800                  12,300                  11,400
<INVENTORY>                                     15,600                  16,400                  16,400
<CURRENT-ASSETS>                               425,500                 420,500                 393,200
<PP&E>                                       2,020,700               1,985,100               1,929,186
<DEPRECIATION>                               1,000,000                 972,300                 940,232
<TOTAL-ASSETS>                               1,752,100               1,736,600               1,671,400
<CURRENT-LIABILITIES>                          513,000                 521,700                 491,400
<BONDS>                                        269,900                 274,300                 277,000
<PREFERRED-MANDATORY>                                0                       0                       0
<PREFERRED>                                          0                       0                       0
<COMMON>                                       135,900                 135,900                 135,700
<OTHER-SE>                                     634,800                 595,500                 551,400
<TOTAL-LIABILITY-AND-EQUITY>                 1,752,100               1,736,600               1,671,400
<SALES>                                              0                       0                       0
<TOTAL-REVENUES>                             1,295,800                 862,600                 429,500
<CGS>                                                0                       0                       0
<TOTAL-COSTS>                                1,032,900                 681,500                 336,000
<OTHER-EXPENSES>                                     0                       0                       0
<LOSS-PROVISION>                                 9,700                   6,500                   2,500
<INTEREST-EXPENSE>                              26,800                  17,700                   8,600
<INCOME-PRETAX>                                250,400                 171,700                  88,300
<INCOME-TAX>                                    87,200                  60,300                  31,100
<INCOME-CONTINUING>                            163,200                 111,400                  57,200
<DISCONTINUED>                                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0
<CHANGES>                                            0                       0                       0
<NET-INCOME>                                   163,200                 111,400                  57,200
<EPS-PRIMARY>                                     1.21                     .82                     .42
<EPS-DILUTED>                                     1.19                     .81                     .42