It was January 15, 1919, around 12:30 PM, on an unseasonably warm day in the North End neighborhood of Boston. Firefighters played cards at their firehouse, kids headed home from school, and cadets trained on the nearby USS Nantucket. Teamsters, blacksmiths, and homemakers were all going about their average days.
Then all hell broke loose as a thunderclap rang out, followed by what sounded like machine gun fire. It was the sound of rivets flying like bullets and thousands of pounds of steel giving way. The ground shook, and a roaring rumble followed. A firefighter jumped from the card game and yelled, “Oh my God! Run!” An unbelievable 15-foot-high wave going 35 mph was headed straight for them. But it wasn’t a wave of water; this wave consisted of 2.3 million gallons of molasses. In minutes, 150 people were injured, and 21 men, women, and children were killed.
A local industry

Credit: Wikimedia Commons // Public Domain
Massachusettes had run on the US molasses trade for over 200 years, with rum being one of the primary products locally made from imported molasses. Boston had as many as 25 distilleries by the 1700s and produced around 200,000 gallons of rum yearly.
Sitting on the waterfront in Boston’s North End neighborhood was a gigantic storage tank built by the Purity Distilling Company designed to hold around two and a half million gallons. The First World War had ended only a few months prior, and soon Prohibition would become law. With that, Purity Distilling was sold to United States Industrial Alcohol (USIA), which continued the production of alcohol for dynamite, smokeless powder, and explosives vital to the war effort.
The reasons for the explosion took years to determine. Immediately after, several theories were suggested, including domestic terrorism. But today, the general understanding is that it was a matter of poor maintenance and significant temperature changes. As it was mid-January, the days leading up to the explosion had been closer to 0 F (-17 C). That day, the temperature climbed to 40 F (4 C). A ship from Puerto Rico had filled the tank near the top only a few days before, and the molasses had been warmed to make it easier to transfer. The cold and warm mix encouraged fermentation and accelerated thermal expansion brought on by unseasonable warmth.
A fast-moving tragedy

Credit: Boston Public Library // CC BY 2.0
Though the initial tragedy was disturbingly swift, the ensuing investigation lasted over half a decade, and the court trial included testimony from nearly 3,000 witnesses.
At the time of the explosion, many people were out and working nearby. A city paving department shack stood near the tank, and a brick firehouse sat on the waterfront side. The nearby elevated railway was in operation, and the Boston and Worcester freight rails ran below. Others were at home, and the first police officer to call in the disaster was hit by the wave from behind while on patrol.
When the tank exploded, the five workers in the shack were smothered immediately. The wave knocked the fire department building on its side and pushed it toward the ocean. This hurled one fireman through a partition, crushed another beneath a pool table, and forced a third into a small crawl space where he tried but failed to keep his head above the molasses. The wave knocked a large truck into the harbor and lifted five train cars off their tracks. Large shards of the ruptured tank traveled fast, killing the workers in the rail freight house and taking down an elevated railway pylon. This sent an elevated railway car swinging down towards Isaac Yetton, who ran towards the harbor. That’s when a wave of molasses swept him away. Houses were knocked off their foundations, with one collapsing and killing housewife Bridget Clougherty.

Credit: Library of Congress // Public Domain
Nearly a dozen horses were also killed. The tremendous viscosity and weight of the molasses threw people and animals around the streets and pushed them under a suffocating blanket. Only 15 dead were found that day, and it took months to recover all the bodies. A week after, a child’s remains were found behind one of the scattered trains, while others were swept out to sea and not discovered until much later. The clean-up was slow, took months, and included around 400 people.
Legal battles and legacy

Credit: Boston Public Library // CC BY 2.0
Needing to find a reason for such an unexpected and gruesome disaster resulted in an extended investigation and a protracted legal battle. United States Industrial Alcohol argued that the culprit was a Bolshevik bombmaker. Everything from poor maintenance to a lack of building codes was blamed. There was even an accusation that USIA painted the outside of the tank brown so that molasses leaks wouldn’t be noticed. A state auditor determined that USIA’s construction manager, Arthur Jell, had not performed any standard safety tests on the tank that had already gone through four years of significant repeated stress.
This was the first class action lawsuit against a major corporation in the US. It’s a case that wasn’t settled until six years later, in 1925. All told that the victims and their families won $628,000 in damages, while more than 100 settlements were made out of court.
The investigation and trial helped shape many modern regulations. Author of the book “Dark Tide: The Great Boston Molasses Flood of 1919,” Stephen Puleo stated in an interview, “Every building construction standard that we sort of take for granted today comes about because of the Molasses Flood.”
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