The city of Leavenworth was started in 1854. It was the first incoporated city in Kansas. The city is south of Forth Leavenworth. The fort is the oldest active Army post west of the Mississippi River. Fort Leavenworth was started in 1827 by Colonel Henry Leavenworth. At first, the fort was outside of the city. On April 12, 1977, the city took over the fort and it became part of the city.