Purity Distilling Company

The Boston Molasses Disaster, also known as the Great Molasses Flood and the Great Boston Molasses Tragedy, occurred on January 15, 1919, in the North End neighborhood of Boston, Massachusetts in the United States.

A large molasses storage tank burst, and a wave of molasses rushed through the streets at an estimated 35 mph (56 km/h), killing 21 and injuring 150.

The event has entered local folklore, and for many decades residents claimed that on hot summer days, the area still smelled of molasses.

The disaster occurred at the Purity Distilling Company Facility on January 15, 1919. The temperature had risen above 40˚ F (4.4˚ C), climbing rapidly from the frigid temperatures of the preceding days. At the time, molasses was the standard sweetener in the United States.

At about 12:30 in the afternoon near Keany Square, at 529 Commercial Street, a molasses tank 50 ft (15 m) tall, 90 ft (27 m) in diameter and containing as much as 2,300,000 US gal (8,700 m3) collapsed. Witnesses stated that as it collapsed, there was a loud rumbling sound, like a machine gun as the rivets shot out of the tank, and that the ground shook as if a train were passing by.

The collapse unleashed a wave of molasses 25 feet (7.6 m) high at its peak, moving at 35 miles per hour (56 km/h). The molasses wave was of sufficient force to damage the girders of the adjacent Boston Elevated Railway's Atlantic Avenue structure and tip a railroad car momentarily off the tracks.

Author Stephen Puleo describes how nearby buildings were swept off their foundations and crushed. Several blocks were flooded to a depth of 2 to 3 feet (60 to 90 cm). Puleo quotes a Boston Post report: 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. 21 People died and 150 people were injured that day.