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, killing 21 and injuring 150. The event has entered local folklore, and residents claim that on hot summer days, the area still smells of molasses.
The disaster occurred at the Purity Distilling Company facility on January 15, 1919, an unusually warm day. Near Keany Square, at 529 Commercial Street, a huge molasses tank 50 ft (15 m) tall, 90 ft (27 m) in diameter and containing as much as 2,300,000 US gal 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 an immense wave of molasses between 8 and 15 ft high, moving at 35 mph (56 km/h), and exerting a pressure of 2 ton/ft². The molasses wave was of sufficient force to break the girders of the adjacent Boston Elevated Railway's Atlantic Avenue structure and lift a train off the tracks. Nearby, buildings were swept off their foundations and crushed. Several blocks were flooded to a depth of 2 to 3 feet
The Boston Globe reported that people "were picked up by a rush of air and hurled many feet." Others had debris hurled at them from the rush of sweet-smelling air. A truck was picked up and hurled into Boston Harbor. Approximately 150 were injured; 21 people and several horses were killed — some were crushed and drowned by the molasses. The wounded included people, horses, and dogs; coughing fits became one of the most common ailments after the initial blast.
It took over 87,000 man hours to remove the molasses from the cobblestone streets, theaters, businesses, automobiles, and homes. The harbor was still brown with molasses until summer.