Historical Marker

Longhorn Army Ammunition Plant

Marker installed: 2007

In 1941, as the United States prepared for eventual entry into World War II, the U.S. Army Ordnance Department approached Monsanto Chemical Company of St. Louis about operating a local plant for production of explosives. Initially called Longhorn Ordnance Works, the plant produced over 400 million pounds of trinitrotolulene (TNT) from 1941 to 1945. After the war, the Army placed the plant on standby status. During the Korean War (1950-1953), the need for munitions rose again, and the Universal Match Corporation, also of St. Louis, managed the site, producing propellant fuel.In 1956, Thiokol Chemical Corporation began manufacturing solid fuel rocket motors here. This highly guarded and classified site grew in a series of five expansions. In 1964, its name changed to the Longhorn Army Ammunition Plant and employment rose to a high of nearly 3,000 personnel. The numbers declined with the end of the Vietnam War and the easing of tensions with the Soviet Union, and employment dropped to less than 1,000 by 1975.In 1987, the United States and the Soviet Union signed the Treaty of Intermediate Nuclear Forces, beginning the elimination of an entire class of missiles. In 1988, the first destruction on American soil of U.S. Pershing I and II rocket motors occurred at the site. Observed by Soviet and U.S. officials, the demolition project continued until 1991. Following official deactiviation in 1995, pollution abatement has steadily provided for adaptive reuse of the former wartime site, now part of the Caddo Lake National Wildlife Refuge. (2007).