Fort Henry on the Missouri River, located at the mouth of the Yellowstone where it enters the Missouri, was established on October 1, 1822 by a party of men led by Major Andrew Henry, who mounted the expedition for the purpose of establishing a fur trade outpost for an area which now encompasses most of Montana, western North Dakota, parts of Wyoming, into Canada. The site of the fort, which was abandoned in 1823, is approximately 20 miles (32 km) southwest of Williston, North Dakota near the Montana - North Dakota state line.