Bad Decisions in History: featuring a Flood of Molasses

When you imagine a flood, you probably picture something like white-capped water spilling over riverbanks or water swirling through the street from a broken pipe or hydrant. Almost certainly something with water, anyway. Not molasses – but that’s just what happened almost a century ago in Boston, Massachusetts.

Bad decision: Failing to properly test the molasses storage tank, which was also poorly constructed; hiding proof of existing leaks.

The idea of molasses flooding the streets is ludicrous, almost amusing, even – until the magnitude of this disaster becomes clear.  The molasses tank was located at the Purity Distilling Company. At over 50 feet tall, the storage tank had a holding capacity of just over 2 million gallons, which is quite a lot of molasses.

The affected area is circled

In January of 1919, the tank failed, while containing tons of molasses. As the rivets of the tank burst, reportedly making a machine-gun like sound, the entire tank collapsed with an earth-shaking rumble and unleashed a tidal wave of molasses that was 25 feet at its highest point, and which crashed through the streets at about 35 miles per hour (56 kilometres). It really gives a different meaning to that old saying, ‘slower than molasses in January’, doesn’t it?

The force of the molasses damaged nearby buildings, shoving them right off their foundations, and tipped a railroad car off the tracks. The area was flooded with a depth of up to 3 feet of molasses. People and animals who had the misfortune to be in the flood zone struggled and thrashed to escape the sticky, viscous liquid. Horses apparently succumbed like flies on fly-paper, and people who were swept off their feet by the initial blast fought to free themselves. Bystanders, police, Red Cross, and army personnel soon waded into the waist-deep mess to help pull out survivors, while others tended to the injured. After four days, the search for victims ended. Many of the deceased were difficult to recognize because they were so coated in molasses. Altogether, the flood claimed 21 lives, injured 150 more people, as well as killing or wounding several horses and dogs. For months afterward, many people suffered from a cough after breathing the sweet, molasses tainted air. The clean-up took weeks, and it’s said the area still smelled like molasses on hot days for years afterward.

How did a terrible disaster like this occur? It was partially to do with the molasses itself, which can be fermented to produce rum, which means that fermented molasses can contain ethanol, the active ingredient in alcohol. Outside factors such as the air temperature also played a role; the temperature rose significantly during a short time period, and would have assisted in raising the pressure within the tank.

These two are the uncontrollable factors, but there were negligent items that contributed to the disaster. The storage tank was also cheaply constructed, and had not been sufficiently tested. An inquiry after the flood proved that standard safety tests for the time, such as filling the tank with water to check for leaks, had never been conducted. In fact, the tank had been leaking the whole time, and it was painted brown in an attempt to hide the leaks (which seem to have been fairly well known anyway, for local residents allegedly collected leaking molasses for their personal cooking use). As well, an investigation many years later found that the steel was only half as thick as it should have been (even for 1919’s less strict building standards) and it did not contain manganese, which mean the tank was quite brittle.

After the disaster, local residents of Boston joined a class-action law suit against the United States Industrial Alcohol Company, which had since bought Purity Distilling. The company attempted and failed to attribute the disaster to an explosion caused by anarchists, and ended up paying hefty settlement fees.

Outcome: 21 deaths, 150 injuries, more deaths and injuries in animals, a gigantic mess that took weeks to clean up, prolonged coughs.


Smashed vehicles and debris sit in a puddle of molasses on Commercial Street on Jan. 16, 1919, the day after a giant tank in the North End collapsed, sending a wave of an estimated 2.3 million gallons of molasses through the streets of Boston.


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