The Great Boston Molasses Flood
A steel storage tank holding about 2.3 million gallons of molasses failed in Boston’s North End, sending a fast-moving wave through streets, buildings, and an elevated railway. Twenty-one people died and roughly 150 were injured. The years-long civil case rejected the owner’s sabotage theory and made deficient design and construction central to the disaster record.
What existed before
The Purity Distilling Company built the tank rapidly in 1915 to store molasses used in industrial alcohol production. Residents reported that it leaked from early in its life. Large structures of this kind faced far less consistent engineering review and permitting than they would later in the century.
Trigger and cause
Soon after a fresh delivery, the tank ruptured near midday. Later engineering work has examined several interacting factors, including thin and inadequately tested steel, flawed riveted joints, internal pressure, temperature change, and the behavior of the molasses itself. No credible evidence supported the company’s claim of an anarchist bombing.
Aftermath
Rescuers worked through wreckage and thickening molasses while the search for victims continued. More than one hundred lawsuits were consolidated into a lengthy proceeding. A court-appointed auditor concluded that structural failure—not sabotage—caused the collapse, and the company paid damages.
Why it matters
The flood is remembered for its surreal material, but the historical lesson is ordinary and durable: warning signs, weak oversight, rushed construction, and an owner’s incentives can turn an industrial container into neighborhood-scale infrastructure risk.
Uncertainty note
Contemporary accounts differ on the wave’s exact maximum height and speed. This file uses rounded quantities and avoids treating later folklore—such as a persistent smell on hot days—as established evidence.