Exhibit 21.1 KNIGHT TRANSPORTATION, INC. SUBSIDIARIES 1. Knight Transportation Services, Inc., an Arizona corporation. 2. Knight Management Services, Inc., an Arizona corporation. 3. Knight Transportation South Central, L.P., a Nevada limited partnership. 4. KTE/Com, LLC, a Delaware limited liability company. 5. KTTE Holdings, Inc., a Nevada corporation. 6. QKTE Holdings, Inc., a Nevada corporation. 7. Quad K Leasing, Inc., an Arizona corporation.