EXHIBIT 21 SIGNIFICANT SUBSIDIARIES OF UNION PACIFIC CORPORATION State of Name of Corporation Incorporation ------------------- ------------- H. W. M. A. Corporation ..................... New York USPCI, Inc. ................................. Delaware Overnite Transportation Company ............. Virginia Union Pacific Holdings, Inc. ................ Utah Union Pacific Railroad Company .............. Utah Missouri Pacific Corporation ................ Delaware Missouri Pacific Railroad Company ........... Delaware Resources Holdings, Inc. .................... Delaware Union Pacific Finance Company ............... Delaware Union Pacific Resources Company ............. Delaware Union Pacific Technologies, Inc. ............ Delaware Skyway Freight Systems, Inc. ................ California