In 1919, a Boston storage tank exploded and unleashed a 25-foot wave of molasses at 35 mph — killing 21 people and leaving the streets smelling sweet for decades.
On January 15, 1919, a 50-foot-tall tank containing 2.3 million gallons of molasses burst open in Boston's North End neighborhood. The resulting wave of molasses stood 25 feet high and traveled at an estimated 35 miles per hour — fast enough to hurl a truck into Boston Harbor and derail a streetcar.
Molasses is a non-Newtonian fluid, meaning its viscosity changes under stress. During the initial burst it thinned and flowed with terrifying speed, sweeping people off their feet and demolishing buildings. Then, as it cooled in the January air, it thickened into a gelatinous trap — making rescue efforts agonizing as victims slowly suffocated in the slowly hardening syrup.
The disaster killed 21 people and injured 150 more, along with numerous horses and dogs. Witnesses described people and animals trapped like flies on flypaper — the more they struggled, the deeper they sank. Anthony di Stasio, a local schoolboy, was carried tumbling on the crest of the wave, nearly choking to death before his mother found him.
The tank was catastrophically defective from the start. It had leaked so badly since 1915 that its owners had simply painted it brown to hide the stains. Local residents had been collecting the leaked molasses for personal use. A 2014 engineering analysis found the steel was half as thick as it should have been, lacked manganese, and had flawed rivets — a disaster waiting to happen.
The company initially tried to blame the disaster on anarchist saboteurs — a convenient claim in the politically charged atmosphere of 1919. A three-year court investigation found otherwise, and the United States Industrial Alcohol Company paid out $628,000 in damages (roughly $11.7 million today). It was one of the first major class-action lawsuits in Massachusetts history.
The cleanup took weeks, with hundreds of workers using salt water and sand to scour the streets. The molasses was tracked across Greater Boston — into subway cars, telephone handsets, homes, and shops. According to local legend, on hot summer days, the North End still smelled faintly of molasses for decades after the flood.