Jefferson Barracks County Park is a 1,702-acre park located on a scenic bluff overlooking the Mississippi River on the site of what once was a major U.S. Army installation. Jefferson Barracks played a significant role in U. S. history for 120 years. Established in 1826, it was the country’s first “Infantry School of Practice” and served as the primary training and gathering place for the Army of the West. Jefferson Barracks replaced Fort Belle Fontaine, the first U.S. Army installation west of the Mississippi River, which suffered from repeated flooding because of its location on the Missouri River. Jefferson Barracks was named in honor of President Thomas Jefferson, who had died on the Fourth of July of the year the post was established.

Jefferson Barracks played an important role in westward expansion serving as a gathering point for troops that established and garrisoned frontier posts, and provided protection for settlers and travelers heading west. During the Civil War Jefferson Barracks served as a major medical facility and a primary ordnance depot for the Union Army. The post has served as a gathering point for troops and supplies bound for service for all major conflicts from the Mexican-American through World War II. Jefferson Barracks also served as the first Army Air Corps basic training site.