Exhibit 21 UNION TANK CAR COMPANY AND SUBSIDIARIES SUBSIDIARIES OF THE REGISTRANT as of December 31, 1998 Jurisdiction Under Which Organized --------------- Atlas Bolt & Screw Company Delaware Atlas Bolt & Screw Company of Canada (1995) Ltd. Canada Deerwood Fasteners International, Inc. North Carolina Enersul Holdings Inc. Alberta Enersul Inc. Alberta E. S. Investments Inc. Alberta The Marmon Group of Canada Ltd. Canada McKenzie Valve & Machining Company Delaware Procor Alberta Inc. Alberta Procor LPG Storage Inc. Alberta Procor Limited Canada Procor Sulphur Services Inc. Alberta Rail Car Associates Limited Partnership Illinois Railserve, Inc. Delaware Railserve Inc. Canada Robertson Inc. Canada Tiger Industries (1997) Inc. Alberta Tiger-Sunbelt Industries, Inc. Delaware Trackmobile, Inc. Georgia Trans Union Fastener Corporation Delaware Uni-Form Components Co. Delaware Union Tank Car Rail Services Company Delaware All subsidiaries listed above are wholly-owned, except for Rail Car Associates Limited Partnership of which the Company is the general partner and has an 80% ownership interest, and are included in the consolidated financial statements incorporated herein. -45-