Did a wave of molasses really kill people in Boston?

“Slow as molasses” is how we describe something that takes forever. So it seems almost impossible that a sticky brown syrup once tore through a city neighbourhood faster than a person could run, flattening buildings and killing people. But that is exactly what happened in Boston just after the First World War.

The short answer

Yes. Shortly after noon on 15 January 1919, a giant tank in Boston’s North End split apart. More than 2.3 million gallons of molasses poured out in a wave estimated at around 15 feet high, moving at roughly 35 miles per hour. It killed 21 people and injured about 150.

The real story

The tank belonged to the Purity Distilling Company, part of the United States Industrial Alcohol Company (USIA). Molasses was not being stored for pancakes; it was raw material for rum and for industrial alcohol used in making munitions. The tank was enormous, more than 50 feet tall and about 90 feet across.

When it gave way, the wave of syrup swept over the waterfront, knocking buildings off their foundations and burying people, horses and carts. Many of the victims died because they were trapped in the thick, heavy liquid and could not breathe. Rescuers struggled to reach them, wading through syrup that clung to everything.

The twist came in court. USIA insisted the tank had been blown up by anarchists, a convenient excuse at a time of real political bombings in the US. But a court-appointed auditor looked at the evidence and concluded the tank had simply been structurally unsound. In 1925 the company was held liable and ordered to pay damages.

Cleaning up took weeks, and locals reportedly claimed that on hot days the neighbourhood smelled of molasses for years afterwards.

Why people get it wrong

Our everyday experience of molasses is a spoonful dribbling slowly out of a jar. That small-scale image makes a deadly flood seem ridiculous. What we forget is that millions of gallons of anything, released all at once from a great height, carries a huge amount of weight and momentum. A slow liquid at the kitchen table becomes a very different beast when a whole tank of it is let go at once.

The story also sounds like a cartoon. A tidal wave of syrup is the sort of thing you would expect in a children’s animation, not a newspaper. Because it seems so absurd, many people file it under “urban legend” until they see the photos of wrecked streets and twisted steel.

It was a genuine tragedy for the families of the 21 people who died, and it remains one of the strangest disasters in American history.

“Slow as molasses? Not when there’s two million gallons of it coming down the street at you, it isn’t.”