K-26 is a 3.601-mile-long (5.795 km) state highway located entirely within Cherokee County, Kansas. It runs from an intersection with U.S. Route 166 (US-166) and US-400 northwest of the Missouri/Kansas/Oklahoma tripoint north to K-66 in Galena. The highway is maintained by the Kansas Department of Transportation (KDOT). The route was designated in 1937 on a roadway that ran from Crestline to the Missouri state line, but was moved to its current location via a series of route re-designations that took place over the following decades, assuming its current route in the mid-1980s.