Jefferson Barracks National Cemetery is an American military cemetery located in St. Louis County, Missouri, just on the banks of the Mississippi River. The cemetery was established after the American Civil War in an attempt to put together a formal network of military cemeteries. It started as the Jefferson Barracks Military Post Cemetery in 1826 and became a United States National Cemetery in 1866.

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.