Boston’s Great Molasses Flood, 1919

Boston was hit by one of the weirdest disasters ever heard of, when the city docksides were deluged by a wave of sticky molasses. Read about the suffering it inflicted and how the city’s streets reeked for years after.

Molasses (Black Treacle) is a thick, heavy substance refined from sugar cane. In Boston, 1919, the Purity Distilling Company used it to ferment ethanol, the stuff used to manufacture alcohol and even munitions at the time.

Shipments were stored in a giant tank on the harbourside which stood 15 m (50 ft) tall by 27 m (90 ft) in diameter and contained as much as 8,700,000L (2,300,000 US gal). At midday in mid-January, possibly due to thermal heating, the stored liquid expanded and the huge container burst open and collapsed.

Witnesses reported that they felt the ground shake and heard a roar, a long rumble similar to the passing of an elevated train; others reported a tremendous crashing, a deep growling, “a thunderclap-like bang!”, and a machine gun-like sound as the rivets shot out of the tank.

The liquid is much heavier than water and so was extremely destructive as a wave smashed and sploshed across the harbour, 8 m (25 ft) high at its peak and moving at 35 mph (56 km/h). Several blocks around were flooded.

The Boston Post reported: “Molasses, waist deep, covered the street and swirled and bubbled about the wreckage… Here and there struggled a form — whether it was animal or human being was impossible to tell. Only an upheaval, a thrashing about in the sticky mass, showed where any life was… Horses died like so many flies on sticky fly-paper. The more they struggled, the deeper in the mess they were ensnared. Human beings — men and women — suffered likewise.

The thick, heavy wave of molasses devastated Boston’s harbourside (

21 people and several horses died, and over a hundred more people were injured. The clean-up took weeks. The event passed into folklore and for years afterwards the streets still reeked sickly sweet on hot Summers’ days.

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