The 1919 Boston Rapid Flood Was Slower Than Molasses

6 min read

Hi everyone, I’m Rick Barron, your host, and welcome to my podcast, That’s Life, I Swear

On January 15, 1919, Boston was hit with a massive flood. The flood rushed through the streets at an estimated 35 miles per hour, killing 21 people and injuring over 150. By the way, the flood wasn’t water, it was molasses. Talk about a sticky situation.

Let’s jump into this 

The Great Molasses Flood of 1919, also known as the Boston Molasses Disaster, was a catastrophic event that occurred on January 15, 1919, in Boston, Massachusetts. It was caused by the sudden rupture of a massive molasses storage tank, which unleashed a 40-foot-high wave of sticky, syrupy molasses that swept through the streets of the city's North End neighborhood.

Purity Distilling Company. Courtesy of: City of Boston

The molasses tank was located on Commercial Street, near the waterfront, and was owned by the Purity Distilling Company, a subsidiary of the United States Industrial Alcohol (USIA) company. 

The tank was 50 feet tall and 90 feet in diameter and contained an estimated 2.3 million gallons of molasses, which was used to produce industrial alcohol, a key ingredient in the manufacture of munitions during World War I.

Some data points to share here. How much is 2.3 million gallons of molasses? Did some digging and found two examples:

1.     Assuming that a standard recipe for chewy ginger molasses cookies requires about 1/4 to 1/2 cups of molasses and that each gallon contains approximately 16 cups, we can estimate that 2.3 million gallons of molasses would yield anywhere from 73 million to 146 million cups of molasses.

 If we further assume that each batch of cookies requires about 1/4 cup of molasses, we could potentially make anywhere from 292 million to 584 million batches of cookies.

2.     Three-and-a-half Olympic size swimming pools

The tank was constructed in 1915, and as mentioned, its purpose was to ferment molasses to produce industrial alcohol. With World War I sweeping across Europe; the munitions industries had an unquenchable thirst for the industrial alcohol needed to make cordite, smokeless gunpowder used in ammunition and artillery shells. 

As is always the case, USIA rushed the construction of the tank to take advantage of lucrative war contracts. It’s always about money. Supervisors and inspecting officials overseeing the building and management of the tank lacked the engineering expertise to spot deficiencies in the tank's materials and construction. USIA was in such a hurry that the first shipment of molasses from Cuba arrived in Boston before the tank could be tested for potential leaks.

Boy, you would think that, adherence to safety would’ve been high on the list. 

Records show that on January 12, 1919, a 600,000-gallon delivery of molasses was delivered to Boston. The following day, the 600,000 gallons was pumped from the S.S. Milerro in Boston Harbor to the storage tank that nearly filled it to its capacity. 

The Great Molasses Flood by Alex Dainis. PhD. Courtesy of: YouTube

A day later, USIA planned to transfer the molasses to railroad tank cars for transport to its distillery in Cambridge, MA. Prior to starting the transfer, it was discovered that the pressure proved too great for the steel tank's walls. The lack of quality control had been over looked too many years and time was about to run out.

Nothing was said about the pressure concerns, and transferring the molasses would start on Wednesday, January 16th. Hold that thought.

Records showed that the day temperatures were hovering around 40 degrees Fahrenheit on January 15th. Other than the standard noise of people walking about, cars going up the street, it was your typical quiet normal day in Boston.  

The serenity was about to come to an abrupt stop. 

It was around 12:40 p.m., people living close by the tank, heard a very loud rumbling noise, which was followed by a loud explosion. No sooner did the explosion occur that people heard the sound of metal ripping as the tank's steel walls tore apart. 

Location of Molasses flood.  Courtesy of Google Maps

The molasses poured quickly into the surrounding streets and into the neighborhoods beyond. Anything and everything in the path of the moving molasses, captured onlookers and suffocating them immediately. Some individuals were so terrified they froze, only to then be washed into the nearby harbor. 

Some of the victims such as 65-year-old Mrs. Bridget Clougherty, was crushed by a collapsed building. She was sitting in her home at 6 Copps Hill Terrace, which extended along Commercial Street, with her daughter and two sons, when the first shock came from the explosion.

The sticky, syrupy substance quickly coated everything in its path, making it difficult for rescuers to reach victims who were trapped in the molasses. It took several days to recover all the bodies of the 21 people who lost their lives in the disaster, including ten-year-old Pasquale Iantosca.

The headlines the next day. Courtesy of: The Boston Post

His father could see his10 year old boy from his upper window. He saw his boy swept up by the molasses.  By the time he got to the street the boy was nowhere to be found. His body was not discovered until sometime mid-January. Pasquale had celebrated his 10th birthday just 10 days prior to the disaster. 

As the wave of molasses made its way toward Boston Harbor, the 40-foot-tall wave shattered homes and businesses, overturned vehicles, toppled telephone poles, snapped the supports of a nearby elevated railway, and knocked a firehouse from its foundation.

The massive wave of molasses racing through the streets hit an estimated speed of 35 miles per hour.

Rescuers spent days sifting through the wreckage as they searched for the injured and dead, and did not recover the last victim from the harbor until May 12, almost four months later. Clean-up crews spent an estimated 87,000 worker hours cleaning streets, buildings, trains, and everything else the sticky syrup touched as horses, pedestrians, and curiosity seekers tracked the brown mess throughout the city.

Devastation from the molasses flood. Courtesy of Getty Images

When the dust settled approximately 150 people were injured, and the damage amounted to about $100 million in today’s money.

The cause of the disaster was found to be a combination of factors, including faulty design and construction of the molasses tank, poor maintenance, and a lack of safety measures. The tank had been built in 1915, and had shown signs of weakness from the start. The steel used in its construction was of poor quality, and the rivets used to hold it together were too small and insufficiently spaced. The tank had also been filled too quickly, causing pressure to build up inside, which eventually caused it to burst. Talk about a major list of oversight.

Researchers at Harvard University determined that the cold winter air caused the molasses to thicken as it rolled through the streets rapidly. This made the syrupy wave even deadlier than it would have been in warmer temperatures. Harvard’s Shmuel Rubinstein, an Associate Professor, told The New York Times in November of 2016, half the people who were killed “died basically because they were stuck in the molasses.”

Over time many studies have been conducted on how and why such a disaster occurred. One such study was performed by a team of Harvard students, working with Nicole Sharp, an aerospace engineer and science communications expert who advised the Harvard students. (She runs the website FYFD, [fuckyeahfluiddynamics] through which she explains the principles of fluid dynamics to people outside academia.)

The Harvard students conducted experiments in a walk-in refrigerator to model how corn syrup, standing in for the molasses, would have behaved in cold temperatures. With that data collected, they applied the results to a full-scale flood, projecting it over a map of the North End. Their results, Ms. Sharp said, generally matched the recorded accounts from the time.

“The historical record says that the initial wave of molasses moved at 35 miles per hour,” Ms. Sharp said, “which sounds outrageously fast.”

Today, the site of the disaster is marked by a plaque that reads: "On January 15, 1919, a molasses tank exploded on this site and hurled tons of molasses through the neighborhood. Twenty-one people died in the disaster. This plaque is dedicated to their memory and to all others who were adversely affected by the tragedy."

Boston Molasses Flood plaque. Courtesy of: Wikipedia

What can we learn from this story? What’s the take away

The Great Molasses Flood of 1919 remains one of the most tragic and unusual disasters in American history. It was a stark reminder of the importance of safety and quality control in industrial processes. 

Don’t cut corners on the important stuff if you want to avoid wipeout risk.

The entire molasses disaster happened because of a combination of impatience and attempting to save a few pennies.

Had they paid added storage costs while the construction team checked the structural integrity, millions of dollars in lawsuits would’ve been avoided, while workers and citizens would’ve avoided harm or death.

Well, there you go. That's life, I swear.

For further information regarding the material covered in this episode, I invite you to visit my website, which you can find on either Apple Podcasts/iTunes or Google Podcasts, for show notes calling out key pieces of content mentioned and the episode transcript.

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