The route number does not follow the numbering convention for U.S. Highways established by the
American Association of State Highway and Transportation Officials. The number 400 implies the route is a spur of U.S. Route 0, which does not exist.
Colorado US 400 begins in Granada at an intersection with US 385. It then
runs concurrently with
US 50 through
Holly east to the Kansas border.
Kansas US 400 and US 50 enter Kansas west of
Coolidge. They run concurrently through
Garden City, where it intersects
US 83 and separate at
Dodge City, which is where it intersects
US 56 and
US 283. It continues southeast from Dodge City and first intersects
US 54 at
Mullinville. US 400 and US 54 begin a long concurrency at Mullinville which passes through
Greensburg,
Pratt and
Kingman before entering
Wichita. While in Wichita, US 400 and US 54 intersect
Interstate 235 and the concurrency of
US 81 and
Interstate 135.
K-96 provides a short freeway connection to
Interstate 35, which is also the
Kansas Turnpike. At
Augusta, US 400 and US 54 enter into another concurrency with
US 77, and US 400 breaks from this concurrency at
Haverhill. a few miles west of
Pratt, Kansas. US 400 continues east through several small towns before turning southeast to go through the
Fredonia area and intersecting
US 75 at
Neodesha. After a brief concurrency with US 75, it turns east, first intersecting
U.S. Route 169 near
Morehead and then
US 59 near
Parsons before finally intersecting
US 69 south of
Pittsburg. It then turns south with US 69 and at
Crestline, follows
US 69A south to
Riverton. US 400 then turns east with
US 166 at
Baxter Springs and the two highways run concurrently eastward into Missouri. The entire section of US 400 in Cimarron is maintained by the city.
Missouri US 400, along with
US 166, terminates at
I-44 about one mile (1.6 km) east of the Kansas-
Missouri state line, three miles (5 km) west of
Joplin. ==History==