The Boston Molasses Disaster or Boston Molasses Flood is one of the more bizarre disasters in American history. On January 15, 1919 a huge molasses tank failed explosively, sending a flood of hot, sticky, sweet molasses through the streets of Boston’s North End.

The steel tank, operated by the Purity Distilling Company, was 58 feet high and 90 feet in diameter, and held something close to its capacity of 2.5 million gallons. When the tank burst, the concussion of the explosion or “rush of air” was strong enough to knock a truck into Boston Harbor. The splitting seams sent rivets shooting out like bullets, and pieces of steel flew out like shrapnel. The real destruction, however, came from a 7 to 15-foot high, 35-MPH wave of molasses with a pressure of 2 tons per square foot. The molasses swept buildings off their foundations, crushed the girders of an elevated railway and swallowed up dogs, horses and people in its path. 21 people were horribly killed – crushed or burned or drowned in molasses. Another 150 victims were injured. It took six months and 87,000 man-hours to clean up the molasses.
As you might expect, over a hundred lawsuits were brought in the months and years following the disaster. Over 3,000 witnesses testified in court, and 45,000 pages of testimony and arguments were generated. The Purity company tried to blame the tank’s failure on an outside explosion, a bomb planted by an anarchist (the disaster occurred right after World War I, when the “anarchy scare” was at its height). The supposed motive was because the molasses was destined to be made into industrial ethyl-alcohol, which was used in the munitions industry. The prosecution argued that the tank was not reinforced properly and was not properly inspected. Other factors could have come into play, such as the fact that the temperature went from 2°F the prior day to an unseasonably warm 41°F the day of the explosion, and internal pressure could have built up in fermentation or other processes. In addition, the tank had only been filled to capacity eight times, putting a cyclical load on the structure. After 6 years, the trials eventually found no evidence for a bomb and laid the blame on the Purity company. Around a million dollars was paid out to claimants (about 12 million today).
A number of urban legends have persisted in the years following the disaster, such as the one which states that on a hot summer day, one can still smell molasses in the North End. Another legend purports the tank was overfilled in expectation of Prohibition (since molasses is also used to distill into rum). Time has distanced us from the tragic nature of the incident and allows us to appreciate the local’s name for it: “The Boston Molassacre”.
Sources:
[1] What caused the great Boston Molasses Flood?, The Massachusetts Historical Society
[2] The Molasses Disaster of January 15, 1919, Yankee Magazine
[3] Jan. 15, 1919: Morass of Molasses Mucks Up Boston, Wired Magazine
[4] Boston Molasses Disaster, Wikipedia