U.S. Route 400

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.

US-50 and US-400 eastbound

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.

US 400/54 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 1.369 miles (2 km) section of US-400 in Cimarron is maintained by the city.[4]

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.

A section of U.S. 400 that ran from Dodge City to Mullinville, Kansas was U.S. Route 154 from 1926 to 1982. It later became K-154 before becoming part of U.S. 400.

Construction on the first section of the East Kellogg improvement project started in August 2015. The project included a redesigned intersection with Webb Road and widened US-54 and US-400 from four lanes to six lanes from Webb Road to Greenwich Road. Construction on a second project began in 2016, to continue widening the highway to a six-lane freeway between Greenwich Road and K-96. Also new bridges will be built over I-35/KTA, new ramps will be constructed from southbound I-35/KTA to westbound US-54/US-400 and from eastbound US-54/US-400 to both northbound and southbound I-35/KTA. In addition, two-lane one way frontage roads on each side of the freeway will be built. Construction for both projects should be completed by late 2021.[6] A two-mile section of the new highway, from Eastern Street to the K-96 junction, opened on November 21, 2019.[7] On April 16, 2020, vandals damaged an estimated $50,000 worth of construction equipment, which included a bulldozer, excavator and an off-road vehicle.[8]