In 1826 General Edmund P. Gaines (Commander of the Western Department of the Army), Brig. General Henry Atkinson (commanding officer of the sixth infantry regiment), explorer William Clark, and Missouri Governor John Miller spent several days searching the banks of the Mississippi River for the perfect location for a new post to replace Fort Bellefontaine. A site near the city of "Vide Poche" or Carondelet, ten miles (16 km) south of St. Louis, was recommended and then approved by Major General Jacob J. Brown, Commanding General of the Army.
On July 10, 1826, two days after the deed to the land was signed, the first military troops -- six officers and 245 enlisted men of Companies A, B, H and I, commanded by Brevet Major Stephen Watts Kearny -- arrived at the new post and started building temporary quarters that they named Cantonment Miller in honor of Governor Miller. In 1827 the military post was formally named Jefferson Barracks in honor of Thomas Jefferson who had died the year before. Even William Clark's son, Meriwether Lewis Clark, Sr. , would join the ranks of Jefferson Barracks. It was also designated the first "Infantry School of Practice.
The first conflict that the men of Jefferson Barracks were involved with was the Black Hawk War in 1832. Troops were deployed from Jefferson Barracks to push "hostile Indians" back into their village in present day Iowa. Chief Black Hawk was captured and brought back to Jefferson Barracks.
In 1832, the United States Regiment of Dragoons were formed and stationed at Jefferson Baracks. The dragoons, trained to fight mounted or dismounted, were the first unit of permanent cavalry in the United States Army. They were formed and stationed at Jefferson Barracks.
During the American Civil War (1861-1865), Jefferson Barracks served as a military hospital for both sides and a recruitment depot for the North. In 1862 construction of the Western Sanitary Commission's hospital facilities began at Jefferson Barracks. By the time that the hospital complex was complete, it could hold 3,000 patients. By the end of the first year of the war, over 5,000 sick and wounded had been admitted and, by the end of the war, well over 18,000 soldiers had been treated at Jefferson Barracks Hospital. In 2002, The Missouri Civil War Museum was founded, which is still being restored today. The MCWM is being brought to life in the old 1905 Post Exchange Building.
During the 1930s, the Civilian Military Training Corps or CMT was held at Jefferson Barracks. Young men could spend one month a year at the post being trained as a soldier, and after three years they could enter the military. Also during that time the Works Progress Administration (WPA) had camps at Jefferson Barracks.
During World War II, Jefferson Barracks was a major reception center for troops being drafted into the military. It also served as a basic training site for the Army, then later was the first Army Air Corps Training Site. During World War II, Jefferson Barracks had a peak area of 1,518 acres (6.14 km²), and had billeting space for 16 officers and 1,500 enlisted persons.
Jefferson Barracks was decommissioned as a military post in 1946 with the end of World War II.
After Jefferson Barracks was decommissioned, portions of the grounds were sold off for construction of houses. Some of the barracks were acquired by the St. Louis County Housing Authority as temporary low-cost housing. Those were demolished in the 1960s and replaced by the current Jefferson Townhomes development. Bishop DuBourg High School was located on the Jefferson Barracks property for several years in the early 1950s. The former Jefferson Barracks School is now used for storage and maintenance; and the former theater is St. Bernadette Catholic Church.
It is now the site of two St. Louis County Parks (Jefferson Barracks County Park and Sylvan Springs County Park), a National Reserve Base, the Jefferson Barracks National Cemetery and a Veterans Administration hospital. Part of the hospital grounds were donated to the Mehlville School District in the 1960s to build Charles S. Beasley Elementary School.
Jefferson Barracks County Park includes several museums that house artifacts and history of Jefferson Barracks while it was an active United States Military Post. During the 1960s and 1970s, portions of Jefferson Barracks County Park were used as a landfill. During the 1980s, an annual balloon race was held in the park. Today, because of its large size, high school cross country races are often held in the park in the fall months, most notably the Hancock Invitational.