Exhibit 21 SUBSIDIARIES OF REGISTRANT Name Under Which State of Subsidiary Name Incorporation Does Business ---------------------------------- ------------- ------------------------------ MNX Carriers, Inc. Delaware MNX Carriers, Inc. Subsidiaries of MNX Carriers, Inc.: Missouri-Nebraska Express, Inc. Iowa Missouri-Nebraska Express, Inc. MNX Transport, Inc. Missouri MNX Transport, Inc. Subsidiary of MNX Transport, Inc.: MNX Trucking, Inc. Missouri MNX Trucking, Inc. Mark VII Transportation Delaware Mark VII Transportation Company, Inc. Company, Inc. Subsidiaries of Mark VII Transportation Company, Inc.: Mark VII Trucking, Inc. Delaware Mark VII Trucking, Inc. Apollo Express, Inc. Kansas Apollo Express, Inc. Neptune Trucking, Inc. Kansas Neptune Trucking, Inc. Jupiter Transportation, Inc. Kansas Jupiter Transportation, Inc. Taurus Trucking, Inc. Kansas Taurus Trucking, Inc. Orion Express, Inc. Kansas Orion Express, Inc. Capricorn Transportation, Inc. Kansas Capricorn Transportation, Inc.