<ARTICLE> 5
<MULTIPLIER> 1,000
       
                             
<PERIOD-TYPE>                   6-MOS
<FISCAL-YEAR-END>                          DEC-31-1998
<PERIOD-START>                             JAN-01-1998 
<PERIOD-END>                               JUN-30-1998
<CASH>                                          20,111
<SECURITIES>                                         0
<RECEIVABLES>                                   89,127
<ALLOWANCES>                                         0
<INVENTORY>                                          0
<CURRENT-ASSETS>                               139,781
<PP&E>                                         755,851
<DEPRECIATION>                                 188,930
<TOTAL-ASSETS>                                 706,702
<CURRENT-LIABILITIES>                           78,675
<BONDS>                                              0
<PREFERRED-MANDATORY>                                0
<PREFERRED>                                          0
<COMMON>                                           483
<OTHER-SE>                                     420,010
<TOTAL-LIABILITY-AND-EQUITY>                   706,702
<SALES>                                        411,385
<TOTAL-REVENUES>                               411,385
<CGS>                                                0
<TOTAL-COSTS>                                  368,200
<OTHER-EXPENSES>                                 (809)
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                               2,244
<INCOME-PRETAX>                                 41,750
<INCOME-TAX>                                    15,865
<INCOME-CONTINUING>                             25,885
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                    25,885
<EPS-PRIMARY>                                      .54
<EPS-DILUTED>                                      .54

<FN>
STOCK SPLIT
On May 13, 1998, the Company issued shares for a five-for-four common stock 
split effected in the form of a twenty-five percent (25%) stock dividend to 
stockholders of record at the close of business on April 27, 1998.  Prior
Financial Data Schedules have not been restated for this stock split.
</FN>