The smoking remains of the Monsanto chemical plant in the aftermath of the Texas City Disaster, in which nearly 600 people were killed by an explosion of ammonium nitrate fertilizer being transported by the SS Grandcamp, 22nd April 1947. (Photo by Keystone/Hulton Archive/Getty Images)

The deadliest industrial disaster in U.S. history occurred on April 16, 1947, in Texas City, Texas. When the French ship SS Grandcamp exploded, a thousand buildings were destroyed and hundreds of people were killed. Among the dead were half the firefighters in the Texas City Fire Department. All of their firefighting equipment was destroyed, too, which made the city more vulnerable to the damage of the second explosion.

Texas City, located on Galveston Bay, was founded in 1893 by a group of investors who dredged a channel for ships and built a railroad connection between the bay and two major railway lines. The town became a major shipping port where oil companies also built refineries, and soon other industries moved in to take advantage of the port. The city grew even faster during World War II when wartime production and shipping of materials went into overdrive. Soon, the U.S. government established War Department ordnance plants in the city to produce ammonium nitrate, widely used in explosives, especially as an oxidizer. Ammonium nitrate is also an effective fertilizer, and the factories switched over to fertilizer production after the war. But the dangers of storing and transporting large amounts of ammonium nitrate weren’t widely understood at that time—a dearth of knowledge that would have deadly consequences for Texas City.

A MASSIVE BLAST

On April 11, 1947, the cargo ship SS Grandcamp arrived in Texas City to pick up a load of ammonium nitrate. Rain delayed the loading process, but by April 16, the ship held around 2300 tons of the fertilizer. When longshoremen arrived to load more, they noticed a fire that seemed to be coming from several layers down in the piles of 100-pound sacks. An official from the Grandcamp didn’t want to use water on the fire because that would damage the cargo but fed steam into the hull instead. This did nothing to extinguish the fire, though—ammonium nitrate produces its own oxygen. So the fire department was summoned, and 27 of the 47 volunteers of the Texas City Fire Department responded, with all four of the department’s trucks.

At 9:12 a.m., the ship’s cargo exploded with such force that it broke windows in Houston, 40 miles away, and was felt 250 miles away in Louisiana. The blast killed all of the firemen, theGrandcamp crew members who were still aboard, and most of the crowd that had gathered to watch the fire. Around a thousand buildings were destroyed, including warehouses at the dock and the nearby Monsanto plant, where 145 workers were killed from the explosion and the resulting 15-foot tsunami. Parts of the ship, some weighing several tons, were propelled high into the air, and metal rained down over the city. Falling shrapnelcaused nearby refineries to catch fire. Two sightseeing planes flying overhead were blasted out of the air. TheGrandcamp’s 2-ton anchor has blown a mile and a half away, and the only other two ships at port, the High Flyer, and the Wilson B. Keene, were also damaged in the explosion; the High Flyer was torn from its mooring and thrown into the Wilson B. Keene.

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