US Route 400 is a real head-scratcher. It primarily runs east-west across southern Kansas, with slight forays into Missouri and Colorado. West of Wichita, US Route 400 is always concurrent with US Route 54 or US Route 50, except for a small transfer between Mullinville and Dodge City. This renders the western half of the route mostly useless. The eastern half of the route splits from US Route 54, and wiggles easterly and southeasterly to a junction just south of Pittsburg, Kansas. From this point along the eastern edge of Kansas, US Route 400 heads south along US Route 69 and US Route 166 to end just barely beyond the Missouri state line, at Interstate 44 near Joplin, Missouri. The western extent of US Route 400, by the way, follows US Route 50 just barely into Colorado, ending in Granada at US Route 385.
My photo of US Route 400 shows a southbound trailblazer seen by those leaving the roundabout with Kansas Highway 66. US Route 400 is running north-south in southeastern Kansas, and at this point, it is duplexed with Alternate US Route 69. This photo was taken near Riverton, Kansas, in October 2024, during the Southwest trip to New Mexico, Texas, and Oklahoma.