The Jefferson Barracks Military Post is located on the Mississippi River at Lemay, Missouri, south of St. Louis. It was an important and active U.S. Army installation from 1826 through 1946. It is the oldest operating U.S. military installation west of the Mississippi River, and it is now used as a base for the Army and Air National Guard. A Veterans Affairs healthcare system campus is located on the southern portion of the base and is also the headquarters for the Veterans Canteen Service.