U.S. Route 400 (US 400) is a mostly east–west U.S. Highway. It was created in 1994. The highway's western endpoint is in Granada, Colorado, at an intersection with US 385. The highway's eastern endpoint is southwest of Joplin, Missouri, near Loma Linda, at an interchange with Interstate 44. It originally ended in Garden City, Kansas; in 1996 it was made longer to its current western endpoint. Its route number does not follow the usual AASHTO numbering scheme, as there is no "parent" US 0.