The Jefferson Barracks Military Post 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.
Jefferson Barracks County Park includes the several museums, museums that house artifacts and history of Jefferson Barracks while it was an active United States Military. The Powder Magazine Museum focuses on the history of Jefferson Barracks from its inception in 1826 until its closure in 1946. The Old Ordnance Room, also once a powder magazine, features temporary exhibits with military themes. The Laborer's House Museum shows a typical mid 1800s family residence. Missouri Civil War Museum, Jefferson Barracks Telephone Museum