On January 15, 1919, the ground near 529 Commercial Street in Boston, Massachusetts, began to tremble. At the nearby Purity Distilling Company, a six-story-tall molasses tank grumbled like a massive stomach with indigestion. The tank’s monumental cache of molasses was awaiting transfer to a processing plant, where it would be used in the production of sweetener, drinking liquor, and alcohol-based munitions.
Moments after the first distressed groan, a sound reminiscent of machine-gun fire echoed in the streets as the tank’s rivets buckled in quick succession. The tank burst in a terrific explosion, throwing massive, ragged chunks of sheet-iron into the surrounding buildings. The Purity offices were flattened by the blast, and a nearby fire station was crushed by a flying section of the iron.
Despite the force of the rupture, initial damage was limited to the buildings adjacent to the tank. The two-and-a-half –million-gallon column of molasses, however, caused a considerable catastrophe as it spread itself out into the North End neighborhood.
Bystanders were swept up in the smothering goo, tossed and rolled through the thick sludge. The migrating wave of brown syrup pushed buildings off their foundations and overturned wagons, carts, horses, and motorcars. It broke the girders of an elevated railroad and tossed a train from its tracks.
Within minutes, several blocks of Boston’s streets were filled with struggling victims, rubble of ruined buildings, assorted wreckage, and two to three feet of sweet, tacky goo.
Rescue efforts began immediately, but most who ventured in became mired in the mess and soon required rescuing themselves. Terrified survivors were seen running away from the chaotic scene covered from head to toe in dark-brown molasses.
The U.S.S. Nantucket was anchored at the Playground Pier a few blocks away, and Lieutenant Commander H.J. Copeland sent over a hundred able-bodied sailors to lend assistance. Police officers, military personnel, and Red Cross nurses slogged through the knee-deep syrup all night long, searching for sticky victims.
In all, 21 lives were lost in the disaster, mostly due to crushing and asphyxiation, and 150 injuries were reported. It is said that a lawyer for Purity arrived on the scene within hours and tried to pin the disaster on anarchist saboteurs, but despite this continued insistence, the company ultimately paid out about $1 million in settlements (equivalent to about $11 million today).
The nearby harbor remained brown through the rest of the winter and spring, and it took more than six months to clean the structures, automobiles, and cobblestone streets of the sticky mess. By coincidence, the 18th Amendment of the U.S. Constitution was ratified the day after the catastrophe, paving the way for Prohibition.
The exact cause of the explosion was never determined, but it is generally attributed to high pressure and a defect in the tank construction. According to some reports, the Purity Distilling Company had neglected to pressure-test the vessel prior to filling it for the first time, and upon its first load of molasses, the outside of the tank was striped with molasses leaks.
Rather than pay for the repairs, Purity opted to paint the tank brown. On that fateful day in 1919, pressure increased due to fermentation of the molasses and unseasonably warm temperatures. This put too much strain on the existing fractures, causing an energetic rupture.
Although, its been almost a century since the flood, they say that on a hot day the streets in some parts of Boston still bleed molasses.