Molasses. Chances are it’s something you don’t have in your pantry, but 100 years ago it was a household staple. Molasses is processed from sugar cane and is used as a sweetener; it is a dark brown, barely viscous liquid. One January day, molasses also became synonymous with death. An industrial accident in Boston, known as the Great Molasses Flood of 1919, caused the sweetener to flow through city streets.
The event highlighted the need for construction regulations and inspections.
It also entered local legend. For decades, Boston residents swore that on a hot day, they could smell molasses.
Causes of the Accident
Molasses was stored on Commercial Street in Boston’s North End in a 50-foot-tall steel holding tank owned by United States Industrial Alcohol. The company produced alcohol from molasses for industrial purposes and for beverages.
During World War I, the demand for alcohol for munitions manufacturing was high, and the company hastily built the holding tank. By 1919, the tank was structurally unsound. It made creaking and groaning noises and had begun to leak molasses. The company, however, did very little to fix it.
Temperature also played a role. Under warmer temperatures molasses has a consistency like honey, but in colder temperatures it’s more like tar.
“Temperatures dipped just below freezing the night following the accident,” Nicole Sharp, an aerospace engineer, told Live Science. “Based on our data, it’s possible the viscosity of the molasses increased by a factor of four or more due to that drop in temperature. That does not sound like such a big difference, but the high viscosity of the molasses was a major factor for rescue work.”
Death by Sticky Liquid
On the morning of the accident, Jan. 15, the temperatures were an unusually warm 40 degrees, after having been only 2 degrees two days prior, and the area was bustling with activity.
In the early afternoon, the tank burst open with “a rumble, a hiss — some say a boom and a swish — and the wave of molasses swept out,” the Boston Post said.
The broken tank released 2.3 million gallons of molasses. The wave, 15-feet-high and moving at 35 miles per hour, swept down Commercial Street with such force that it destroyed everything in its wake. People and horses drowned while others were injured or killed from debris or being pushed into objects.
The wave caused buildings to be swept off their foundations.
“I was in bed on the third floor of my house when I heard a deep rumble,” survivor Martin Clougherty said. “When I awoke, it was in several feet of molasses.”
The wave traveled half a mile before it dissipated.
Rescuers arrived almost immediately, but they had difficulty wading through waist-deep molasses.
The disaster killed 21 people and injured 150. The victims were between 10 and 78 years old.
Legacy of the Great Molasses Flood of 1919
United States Industrial Alcohol blamed anarchists for the tower’s failure.
While this explanation may have been plausible during the war, an investigation revealed the failure had been caused by poor workmanship. The man who oversaw construction of the tower not only wasn’t an engineer, he couldn’t read blueprints.
Over the course of five years, 119 lawsuits were filed against the company. In 1925, a judge ruled the company was liable for the accident and forced the company to pay $628,000 in damages to flood victims and their family members.
In the disaster’s aftermath, the Boston Building Department began requiring architects or engineers sign off on all relevant calculations related to building plans. Not long after, every state required engineers to achieve professional certification.
The flood caused about $100 million in damages, in today’s dollars, according to the Massachusetts Foundation for the Humanities.
It took more than over 80,000 man-hours to clean up the mess.
Updated: 27 October 2020