BPL on Wikimedia

Imagine going about your day, minding your own business, when suddenly, a huge wave of almost black, sludgy liquid comes hurtling towards you. This nightmare sequence became many Bostonites' reality one January day in 1919. 

North Boston was home to a huge storage tank that stood 50 feet tall, 90 feet in diameter, and contained up to 2.3 million gallons of molasses. A sudden fluctuation in temperature caused the tank to rise from below freezing to over 40 degrees Fahrenheit too rapidly. This, combined with a fresh load of warm molasses that had been offloaded the day before, caused the tank to burst open and collapse, unleashing a tidal wave—some reports say 25 feet high—of dark, thick, gooey syrup, moving at nearly 35 miles per hour. 

What followed was one of the most bizarre and devastating disasters in American history, now known as the Great Molasses Flood. The tragedy killed 21 people, injured 150 more, left the entire neighborhood coated in molasses that took months to clean up, and completely demolished buildings near the tank.

Even worse than a tsunami

not specified on Wikimedia

Molasses is a non-Newtonian fluid, meaning its consistency changes under stress. In the case of the flood, it could move with great speed, and then become viscous, especially given the cold winter weather. 

"A wave of molasses is even more devastating than a typical tsunami...In 1919 the dense wall of syrup surging from its collapsed tank initially moved fast enough to sweep people up and demolish buildings, only to settle into a more gelatinous state that kept people trapped," according to a 2013 paper in Scientific America.

Army, police, Red Cross, and military personnel arrived on the scene to rescue people. However, they found that wading through molasses was nearly impossible; it clung to clothing, weighed people down, and hardened quickly as temperatures dropped. Many victims died not from impact, but from being trapped and unable to breathe under the thick, heavy syrup. The molasses flood even swept some victims into the Boston Harbor, only to be found several months later. 

The aftermath

As anyone who's had to wipe up molasses can guess, cleanup was an ordeal all its own. Molasses coated streets, sidewalks, and buildings, seeping into basements and clinging to everything it touched. Crews used seawater pumps, sand, and brooms, but even months later, residents said the neighborhood smelled like molasses every time the weather warmed. 

The city's residents brought a precedent-setting class-action lawsuit against the company who built the tank. The company tried to make a bogus claim that the tank was blown up by anarchists, but the court ruled against them. The tank was apparently so poorly constructed that it had been leaking since say one. The company had it painted brown so it wouldn't be obvious. They also neglected basic safety tests and ignored warning signs. The company had to pay $628,000 ($11.4 million in modern currency) in damages. This was one of the first major examples of corporate accountability in the U.S. courts and helped pave the way for modern building regulations and engineering standards. 

The Great Molasses Flood may sound too wacky to be true, but it was a real, catastrophic event caused by corporate neglicence. People suffocated under pools of molasses, but at least it wasn't in vain. The event reshapes safety laws in ways that still protect us today.