At about 12:30 on a mild Wednesday afternoon, the rivets on a large 50-foot-high tank on Commercial Street containing more than 2,000,000 gallons of molasses began to pop and a dull roar followed as the tank suddenly failed and quickly collapsed.

The collapse unleashed a wave of molasses 25 ft high moving at 35 mph. The wave knocked buildings off their foundations and was sufficiently strong enough to heavily damage the steel supporting the nearby Boston Elevated Railway on Atlantic Avenue.

Twenty-one people died with victims ranging in age from 10 to 78 years old. More than 150 were injured and the cleanup took about 300 people weeks. Boston Harbor was reportedly brown with molasses until the summer of 1919.