The area in which Fort Leavenworth sits was part of the Louisiana Purchase, the 828,800 square mile parcel of French territory bought by President Jefferson in 1803. In early July 1804, Meriwether Lewis, William Clark, and the Corps of Discovery passed through the area.
The fort sits on a high bluff, about 300 feet above the Missouri River. This position above the water line is what first attracted Colonel Henry Leavenworth in May 1827. Originally, COL Leavenworth and his men were ordered to select a location on the eastern bank of the Missouri River for a cantonment that would serve to protect the Santa Fe Trail. However, due to potential flooding Leavenworth selected a location on the western side, which would later become the state of Kansas