K-99 is a state highway in the U.S. state of Kansas. The highway runs 234.473 miles (377.348 km) from Oklahoma State Highway 99 (SH-99) at the Oklahoma state line near Chautauqua north to Nebraska Highway 99 (N-99) at the Nebraska state line in Summerfield. K-99 connects Emporia with several smaller county seats to the south and north, including Sedan, Howard, Eureka, Alma, and Westmoreland while passing through the Flint Hills of eastern Kansas.

U.S. Route 400 is a 481.306-mile-long (774.587 km) mostly east–west U.S. Highway, commissioned in 1994. The highway's western terminus is in Granada, Colorado, at an intersection with US 385. The highway's eastern terminus is southwest of Joplin, Missouri, near Loma Linda, at an interchange with Interstate 44, with which it shares with US 166. It originally ended in Garden City, Kansas; in 1996 it was extended to its current western terminus.