K-10 is a 38 mile (61 km) state highway in the U.S. state of Kansas. It was originally designated in 1929. It is mostly a controlled-access freeway, linking Lawrence to Lenexa. It provides an important toll-free alternate route to Interstate 70 (the Kansas Turnpike). Several scenes for the controversial TV-movie The Day After were filmed on the highway in 1982 portraying a mass exodus evacuating the Kansas City area on I-70.

The highway's western end begins as a two lane highway at I-70 exit 197 just west of Lawrence. It partially bypasses the city to the south to U.S. Route 59, providing access to Clinton Lake. K-10 turns north on US-59 for about 1½ miles (overlapping it) before turning east on 23rd Street. After exiting Lawrence east-bound, it becomes a freeway, passing through the city of Eudora, and then the cities of De Soto and Olathe, suburbs of Kansas City. It then terminates at an interchange with Interstate 435 in Lenexa.

K-10 originally extended west of Lawrence to Herington, via Alta Vista, Alma, and Topeka. In 1956 the portion between Topeka and K-99 near Alma was designated as US-40 in preparation for upgrading this stretch to Interstate standards (for I-70). The segment between Alta Vista and Herington was redesignated as K-4 and K-10 was truncated eastward to Lawrence.

The process of upgrading K-10 to a freeway was begun in 1974. The first section completed was the section from De Soto to the junction with K-7, opening on November 8, 1976. The freeway was finally completed on December 18, 1984, when the stretch from K-7 to I-435 was completed. The old two-lane roadbed of K-10 was turned over to the counties to use as a secondary route. In Douglas County it became CR 442, although many of the locals, especially in Eudora, commonly refer to it as Old K-10.

The portion of K-10 between the Edgerton Road exit and the DeSoto interchange at former K-285 (now Lexington Avenue) was used in the movie The Day After and, for the purposes of the film, was temporarily redesignated Interstate 70.

The bypass of the west side of Lawrence (the South Lawrence Trafficway) was completed in November 1996. Prior to the opening of the Trafficway, K-10 had ended at the junction of US-40 and US-59 in Lawrence.

Completion of the eastern leg of the Trafficway has been long delayed by lawsuits from environmentalist groups and Haskell University. According to the Lawrence Journal-World, these lawsuits have finally been settled, and construction of the Trafficway may now resume. The Kansas Department of Transportation has a plan in place for the alignment of the Trafficway and hopes to have it completed sometime between 2015-2018.