The Great Molasses Flood, also known as the Boston Molasses Disaster, was a disaster that occurred on January 15, 1919, in the North End neighborhood of Boston, Massachusetts.
A large storage tank filled with of molasses, weighing approximately burst, and the resultant wave of molasses rushed through the streets at an estimated , killing 21 and injuring 150 people. The event entered local folklore and residents reported for decades afterwards that the area still smelled of molasses on hot summer days. Possibly due to the thermal expansion of the older, colder molasses already inside the tank, the tank burst open and collapsed at approximately 12:30p.m. Witnesses reported that they felt the ground shake and heard a roar as it collapsed, a long rumble similar to the passing of an elevated train; others reported a tremendous crashing, a deep growling, "a thunderclap-like ", and a sound like a machine gun as the rivets shot out of the tank. and tip a streetcar momentarily off the railway's tracks. Stephen Puleo describes how nearby buildings were swept off their foundations and crushed. Several blocks were flooded to a depth of . Puleo quotes a report from The Boston Post: