Fort Riley is a United States Army installation located in North Central Kansas, on the Kansas River, also known as the Kaw, between Junction City and Manhattan. The Fort Riley Military Reservation covers 100,656 acres (407 km²) in Geary and Riley counties and includes two census-designated places: Camp Funston, Camp Forsyth, Camp Whitside and Custer Hill. The fort has a daytime population of nearly 25,000. The zip code is 66442.