The Day Boston Drowned in 2.3 Million Gallons of Molasses

It sounds like the setup to a bad joke. A tank of molasses bursts in downtown Boston and a tidal wave of syrup tears through a neighbourhood. Then you look at the numbers and the joke stops being funny.

A Tank That Should Not Have Been There

The Purity Distilling Company put up a 50-foot steel tank on Commercial Street in 1915 to hold molasses bound for industrial alcohol, much of it destined for munitions during the First World War. The tank was rushed through construction, never properly pressure-tested, and leaked so badly that locals collected the runoff in buckets. The company painted it brown so the seepage would blend in.

Lunchtime, January 15, 1919

Around 12:30 PM the tank ruptured with a sound witnesses compared to a machine gun as the rivets popped loose. Out came 2.3 million gallons of warm molasses. The wave hit Commercial Street at roughly 35 mph and rose up to 15 feet in places. It snapped an elevated railway support, crushed firehouse walls, and pushed buildings off their foundations.

The Toll

21 people lost their lives and around 150 were injured. Rescuers spent four days pulling victims out of the hardening syrup. Horses that could not break free had to be put down by police. The Red Cross set up a relief station that stayed open for weeks.

The Tank Did Not Blow Up on Its Own

The United States Industrial Alcohol Company, which owned Purity Distilling, tried to blame anarchists. It did not work. A court-appointed auditor heard three years of testimony and ruled the tank was poorly designed and dangerously thin-walled. A fresh warm load had been pumped in the day before on top of colder molasses, and the resulting pressure was too much for the defective shell.

The First Big Class Action

119 residents filed what became one of the first successful class-action lawsuits in Massachusetts history. The case dragged on for six years. In 1925 USIA paid about $628,000 in damages, roughly $11 million in today's money. Families of those who died received around $7,000 each. The case helped push every state toward requiring licensed engineers to sign off on structural plans.

A Smell That Would Not Leave

Historian Stephen Puleo, who wrote Dark Tide, the definitive book on the disaster, has said a Boston Gas meter reader told him he could still smell molasses in North End basements into the 1960s. Locals insisted hot summer days brought the scent back for decades. Today a small plaque at the Langone Park entrance is the only marker left at the site.