Longhorn Army Ammunition Plant
Karnack, Harrison County, Texas
Marker Inscription
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)
Erected by Texas Historical Commission
The Story
When the United States braced for World War II, the Army turned to Monsanto to run a new East Texas plant that poured out more than 400 million pounds of TNT between 1941 and 1945. The site never truly stood down: it made propellant during the Korean War, and from 1956 Thiokol built solid-fuel rocket motors here, employing nearly 3,000 workers by the Vietnam era. Fittingly, in 1988 it became the first place on American soil where U.S. Pershing missiles were destroyed under an arms-reduction treaty with the Soviet Union.
Why it matters
From TNT to rocket motors to Cold War disarmament, the plant is a single site where much of the twentieth century's American arms story—hot war, Cold War, and its unwinding—played out.
The story behind this marker
AI contextThe era
The Longhorn story opens in 1941, in the tense months before the United States was fully drawn into the Second World War. The nation was racing to arm itself, and that meant building, almost overnight, an industrial base capable of producing munitions on a scale never before attempted. Quiet rural places all across the country were suddenly chosen to host enormous new war plants, and this corner of Harrison County, near Karnack in East Texas, became one of them.
The decades that followed read like a timeline of modern American conflict. The plant that produced explosives for World War II did not simply close when peace came; it was placed on standby, then reactivated for the Korean War, then reinvented again for the missile age. Its history tracks the country's passage from the hot wars of the 1940s and 1950s into the long, watchful decades of the Cold War.
That this all unfolded on land now folded into a national wildlife refuge gives the site a striking arc. A place built to make war became, in time, a place given back to nature, its story bending from mass production of explosives toward disarmament and restoration.
People & events
It began with a phone call of sorts from the government to industry. In 1941 the U.S. Army Ordnance Department approached the Monsanto Chemical Company of St. Louis to run a new explosives plant here, first called Longhorn Ordnance Works. Between 1941 and 1945 it poured out more than four hundred million pounds of TNT, an almost unimaginable quantity of the explosive that filled the shells and bombs of the war effort.
After the war the plant did not truly rest. During the Korean War of the early 1950s, the Universal Match Corporation, also of St. Louis, managed the site and produced propellant fuel. Then, in 1956, the Thiokol Chemical Corporation began manufacturing solid-fuel rocket motors here, and the plant entered its most secretive era. Heavily guarded and classified, it expanded five times over, was renamed the Longhorn Army Ammunition Plant in 1964, and at its peak employed nearly three thousand people. As the Vietnam War wound down and tensions with the Soviet Union eased, that workforce shrank to under a thousand by 1975.
The most dramatic chapter came near the end. After the United States and the Soviet Union signed a landmark treaty in 1987 to eliminate an entire class of missiles, this site witnessed, in 1988, the first destruction on American soil of U.S. Pershing I and II rocket motors. Soviet and American officials watched together as the work proceeded, continuing until 1991. The plant was officially deactivated in 1995, and in the years since, cleanup has steadily returned the land to new life as part of the Caddo Lake National Wildlife Refuge.
Its place in the American story
Few single sites hold so much of the twentieth-century American arms story in one place. Longhorn is a rare spot where you can trace, on a single patch of ground, the arc from the industrial mobilization of World War II, through the munitions demands of Korea, into the solid-fuel rocketry of the Cold War, and finally to the extraordinary spectacle of weapons being deliberately dismantled.
The World War II chapter alone illustrates one of the least glamorous but most decisive facts of that conflict: it was won as much in factories as on battlefields. Plants like this one, spun up in rural America and staffed by ordinary workers, produced the sheer tonnage of explosives that modern warfare consumed. The scale of output here is a reminder of how total the war effort truly was.
But the site's deepest significance may lie in its ending. The 1987 treaty between the superpowers was a genuine turning point, the first agreement to eliminate a whole category of nuclear-capable missiles, and the destruction carried out here, watched by officials from both nations, made that abstract diplomacy physical and verifiable. That a place built to manufacture the tools of war became a place to destroy them, under the eyes of a former adversary, captures the hopeful, uneasy unwinding of the Cold War better than almost any monument could.
If you visit
This is a place where history and landscape have quite literally traded roles, and that is what makes it worth contemplating. The former wartime site is now bound up with the Caddo Lake National Wildlife Refuge, a country of cypress, water, and wildlife in far East Texas. Standing in such surroundings, it takes an act of imagination to picture the guarded, classified plant that once hummed here around the clock.
Let the layers of the story settle over you: hundreds of millions of pounds of explosives made for one war, propellant for another, rocket motors built in secrecy for the Cold War, and finally missiles destroyed on this very ground while officials from both superpowers looked on. Few landscapes ask you to hold so many chapters of the modern era at once.
Because this was an industrial and, for a time, contaminated site now undergoing long-term restoration, approach it as a place to reflect rather than to roam freely, and respect any posted guidance about where the public may go. For a traveler exploring the Caddo Lake area, it adds a profound dimension to the region's natural beauty, a reminder that this quiet water country once stood at the center of America's twentieth-century story of war and its unwinding.
Written by AI to add context, grounded in the marker’s inscription and the historical record. The inscription above is the original, unaltered text.
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Related events
- · World War II
- · Korean War
- · INF Treaty missile destruction
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