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 2.3 million US gal (8,700 m3) of molasses, weighing approximately 13,000 short tons (12,000 t), burst, and the resultant wave of molasses rushed through the streets at an estimated 35 mph (56 km/h), killing 21 and injuring 150. The event entered local folklore and residents claimed for decades afterwards that the area still smelled of molasses on hot summer days.