Great Molasses Flood
Imagine a wave—not of water, but of thick, sticky molasses—surging through city streets at incredible speed, demolishing buildings, and trapping everything in its path. This wasn't a nightmare; it was the chilling reality of the Great Molasses Flood, a disaster that swept through Boston's North End on a January afternoon over a century ago. A catastrophic engineering failure, coupled with unusual weather, turned a simple industrial tank into a deadly force. Molasses, a deceptively benign substance, behaved like a devastating non-Newtonian fluid, first rushing like a tsunami and then hardening into a deadly trap. The disaster led to a landmark class-action lawsuit and significantly improved safety regulations in construction and engineering.
AI Summary
Imagine a wave—not of water, but of thick, sticky molasses—surging through city streets at incredible speed, demolishing buildings, and trapping everything in its path. This wasn't a nightmare; it was the chilling reality of the Great Molasses Flood, a disaster that swept through Boston's North End on a January afternoon over a century ago.
- A catastrophic engineering failure, coupled with unusual weather, turned a simple industrial tank into a deadly force.
- Molasses, a deceptively benign substance, behaved like a devastating non-Newtonian fluid, first rushing like a tsunami and then hardening into a deadly trap.
- The disaster led to a landmark class-action lawsuit and significantly improved safety regulations in construction and engineering.
The Day the City Drowned in Sweetness
On January 15, 1919, the lives of many Bostonians changed forever. Take Anthony di Stasio, for example. Walking home from school with his sisters, he was suddenly engulfed—picked up by an immense, dark wave and carried along its crest, tumbling like a surfer on an impossible tide.
The viscous wave eventually grounded him, rolling him like a pebble as it lost momentum. He could hear his mother calling, but his throat was so clogged with the smothering goo he couldn't answer. He passed out, only to awaken to the terrified faces of his sisters, staring at the unimaginable scene around them.
The Unexpected Deluge
What Anthony experienced was the Great Molasses Flood, also known as the Boston Molasses Disaster. At approximately 12:30 p.m., a colossal storage tank at 529 Commercial Street in Boston's North End explosively ruptured, unleashing its sticky contents.
This wasn't just a leak; it was a cataclysm. A wall of molasses, initially estimated at 25 feet high, surged through the streets at an incredible 35 miles per hour. It buckled elevated railway tracks, crushed buildings, and inundated the neighborhood under feet of thick syrup.
The tank held an astonishing 2.3 million US gallons of molasses, weighing approximately 13,000 short tons. The resultant wave killed 21 people and injured 150, leaving a harrowing imprint on the city that would linger for decades—both in memory and in scent.
What Was It For?
So, why was such an enormous quantity of molasses stored in the heart of Boston? This sweet syrup was a crucial industrial commodity. It could be fermented to produce ethanol, an active ingredient in alcoholic beverages, but more importantly for the time, a key component in munitions production.
The facility belonged to the Purity Distilling Company. Molasses arrived by ship at Boston Harbor, was offloaded into this enormous tank, and then piped to Purity's ethanol plant in nearby Cambridge. The tank itself was a formidable structure: 50 feet tall and 90 feet in diameter.
The Unraveling
On January 15, 1919, Boston experienced an unseasonably warm spell, with temperatures rising rapidly to over 40 degrees Fahrenheit. Just the day before, a fresh shipment of molasses had arrived, warmed to reduce its viscosity and make it easier to transfer into the tank.
This sudden warmth, combined with thermal expansion of the colder, older molasses already inside the poorly constructed tank, proved to be a fatal combination. Witnesses described feeling the ground shake, followed by a deafening roar—some likened it to a passing elevated train, others to a thunderclap or even machine-gun fire as rivets shot out of the tank.
A Wave Like No Other
Molasses is significantly denser than water—about 40% denser, in fact. This high density meant the stored molasses possessed an immense amount of potential energy, which was unleashed in an instant when the tank failed. This energy propelled the thick liquid forward with devastating force.
The resulting wave was powerful enough to bend steel girders of the adjacent elevated railway, tipping a streetcar momentarily off its tracks. Nearby buildings were swept off their foundations and utterly crushed, leaving blocks of the North End submerged under a syrupy deluge two to three feet deep.
The scene was horrific. Contemporary reports describe molasses, waist-deep, swirling and bubbling amidst the wreckage. 'Here and there struggled a form—whether it was animal or human being was impossible to tell. Only an upheaval, a thrashing about in the sticky mass, showed where any life was.'
The dense fluid became a death trap. 'Horses died like so many flies on sticky fly-paper. The more they struggled, the deeper in the mess they were ensnared. Human beings—men and women—suffered likewise,' wrote The Boston Post.
The Paradox of Fluidity
Molasses is a non-Newtonian fluid, meaning its viscosity changes under stress. Under immense pressure and heat, it thins and flows more quickly—a property called shear-thinning. This is why the initial wave moved with such astonishing speed.
However, as the wave spread and cooled in Boston's winter air, its viscosity dramatically increased. A 2013 article in Scientific American explained: 'A wave of molasses does not behave like a wave of water. [...] 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.'
The initial rush of air alone was powerful enough to hurl people many feet. But after that initial blast, the molasses quickly became a thick, sticky, cold mass, making rescue efforts incredibly difficult. Many victims were crushed or drowned by the molasses or the debris it carried, while others were trapped, slowly suffocating.
The Impossible Rescue
The first responders to the devastating scene were 116 cadets from the USS Nantucket, a training ship docked nearby. They ran through the knee-deep flood of molasses, pulling out survivors, while others tried to manage the growing crowds of curious onlookers.
Soon, Boston Police, the Red Cross, and Army and Navy personnel arrived. Red Cross nurses bravely dove into the molasses, while doctors and surgeons set up a makeshift hospital in a nearby building to care for the numerous injured.
The rescue was agonizingly slow and arduous. The density of the molasses made movement incredibly difficult, and it took four days before the search for victims was officially called off. Many of the deceased were so thoroughly coated in molasses that they were hard to identify, and some were swept into Boston Harbor, their bodies not recovered for months.
Uncovering the Causes
An investigation into the disaster revealed a shocking tale of negligence and engineering failures. The tank, constructed only a few years earlier, had been leaking from day one. It was poorly built and insufficiently tested, a ticking time bomb waiting for the right conditions.
The inquiry exposed that Arthur Jell, the treasurer for the United States Industrial Alcohol Company (USIA), which owned Purity Distilling, had no architectural or engineering experience. He had overseen the tank's construction, neglecting basic safety tests like adequately filling it with water to check for leaks.
Worse, USIA ignored numerous warning signs, including loud groaning noises the tank made every time it was filled. The leaks were so pervasive that the company painted the tank brown to camouflage the seeping molasses. Local residents even collected the leaked syrup for home use, unaware of the lurking danger.
Modern engineering analysis conducted in 2014 confirmed the fatal flaws. The steel used was only half as thick as it should have been, even by the standards of the era. It also lacked manganese, making it more brittle. Furthermore, the tank's rivets were flawed, and cracks had begun forming at the rivet holes near a manhole cover at the tank's base.
Some historians suggest that the company was rushing to fill the tank to capacity to outpace the impending Prohibition, as the Eighteenth Amendment was ratified the very next day. This pressure to produce may have overshadowed critical safety concerns, with tragic consequences.
Harvard's Modern Look
In 2016, a team from Harvard University conducted extensive studies, using old maps, weather reports, and even modeling the flood with cold corn syrup. Their research confirmed the initial high speed of the molasses and clarified its behavior.
The warmer molasses added just before the burst initially lowered the overall viscosity. However, as the dense liquid spread into the cold January air, it rapidly cooled and thickened, transforming from a fast-moving wave into a gelatinous, inescapable trap. This sudden increase in viscosity sealed the fate of many caught in its path, hampering rescue efforts before victims could suffocate.
The Long Aftermath
In the wake of the disaster, 119 residents filed a landmark class-action lawsuit against USIA. It was one of the first such suits in Massachusetts and proved to be a pivotal moment in the development of modern corporate regulation.
USIA initially tried to blame anarchists, claiming the tank was bombed because its alcohol could be used for munitions. However, a court-appointed auditor spent three years investigating and ultimately found USIA responsible, ordering them to pay $628,000 in damages—the equivalent of over $11 million today.
A City Cleans Up
The cleanup effort was monumental. Crews used saltwater from fireboats to wash away the molasses and spread sand to absorb it. Boston Harbor itself remained brown with molasses until the summer. The immediate area took weeks to clean, and the molasses tracked by rescuers and curious sightseers spread throughout Greater Boston.
Molasses was found everywhere: on subway platforms, inside train cars, on pay telephone handsets, and even in homes. It became a sticky, pervasive part of daily life, with reports stating, 'Everything that a Bostonian touched was sticky' for a long time afterward.
Article
Great Molasses Flood
The Great Molasses Flood, also known as the Boston Molasses Disaster, was a disaster that occurred on January 15, 1919, in the North End neighborhood of Boston, Massachusetts.
A large storage tank filled with 2.3 million U.S. gallons (8,700 cubic meters) of molasses, weighing approximately 13,000 short tons (12,000 metric tons) burst, and the resultant wave of molasses rushed through the streets at an estimated 35 miles per hour (56 kilometers per hour), killing 21 and injuring 150 people. Following a two-week long cleanup effort, the event entered local folklore and residents reported for decades afterwards that the area still smelled of molasses on hot summer days.
Background
Great Molasses Flood
Coverage from The Boston Post
Molasses can be fermented to produce ethanol, the active ingredient in alcoholic beverages and a key component in munitions. The disaster occurred in Boston's North End at the Purity Distilling Company facility at 529 Commercial Street near Keany Square. A considerable amount of molasses had been stored there by the company, which used the Commercial Street tank, located adjacent to Boston Harbor, to offload molasses from ships and store it for later transfer by pipeline to the Purity ethanol plant situated between Willow Street and Evereteze Way in nearby Cambridge. The molasses tank stood 50 feet (15 meters) tall and 90 ft (27 m) in diameter, and contained as much as 2.3 million US gal (8,700 m3).
Flood
Great Molasses Flood
Modern downtown Boston with molasses flood area circled
On January 15, 1919, temperatures in Boston had risen above 40 degrees Fahrenheit (4 degrees Celsius), climbing rapidly from the frigid temperatures of the preceding days. On the previous day, a ship had delivered a fresh load of molasses, which had been warmed to decrease its viscosity for transfer.
Possibly due to the thermal expansion of the older, colder molasses already inside the tank, the tank burst open and collapsed at approximately 12:30 p.m. Witnesses reported that they felt the ground shake and heard a roar as it collapsed, a long rumble similar to the passing of an elevated train; others reported a tremendous crashing, a deep growling, "a thunderclap-like bang!", and a sound like a machine gun as the rivets shot out of the tank.
The density of molasses is about 1.4 metric tons per cubic meter (12 pounds per US gallon), 40% denser than water, resulting in the molasses having a great deal of potential energy. The collapse translated this energy into a wave of molasses 25 ft (8 m) high at its peak, moving at 35 mph (56 km/h). The wave was of sufficient force to drive steel panels of the burst tank against the girders of the adjacent Boston Elevated Railway's Atlantic Avenue structure and tip a streetcar momentarily off the railway's tracks. Stephen Puleo describes how nearby buildings were swept off their foundations and crushed. Several blocks were flooded to a depth of 2 to 3 ft (60 to 90 cm). Puleo quotes a report from The Boston Post:
Molasses, waist deep, covered the street and swirled and bubbled about the wreckage [...] Here and there struggled a form—whether it was animal or human being was impossible to tell. Only an upheaval, a thrashing about in the sticky mass, showed where any life was [...] Horses died like so many flies on sticky fly-paper. The more they struggled, the deeper in the mess they were ensnared. Human beings—men and women—suffered likewise.
As molasses is a non-Newtonian fluid, its viscosity changes under stress, thinning and flowing quickly under pressure and heat. During the flood, this shear-thinning resulted in unexpected speed. A 2013 article in Scientific American stated:
"A wave of molasses does not behave like a wave of water. [...] 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."
The Boston Globe reported that people "were picked up by a rush of air and hurled many feet". Others had debris hurled at them from the rush of sweet-smelling air. A truck was picked up and hurled into the harbor. After the initial wave, the molasses became viscous, exacerbated by the cold temperatures, trapping those caught in the wave and making it even more difficult to rescue them. About 150 people were injured, and 21 people and several horses were killed. Some were crushed and drowned by the molasses or by the debris that it carried within. The wounded included people, horses, and dogs; coughing fits became one of the most common ailments after the initial blast. Edwards Park wrote of one child's experience in a 1983 article for Smithsonian:
Anthony di Stasio, walking homeward with his sisters from the Michelangelo School, was picked up by the wave and carried, tumbling on its crest, almost as though he were surfing. Then he grounded and the molasses rolled him like a pebble as the wave diminished. He heard his mother call his name and couldn't answer, his throat was so clogged with the smothering goo. He passed out, then opened his eyes to find three of his four sisters staring at him.
Aftermath
Great Molasses Flood
Damage to the Boston Elevated Railway caused by the burst tank and resulting flood
First to the scene were 116 cadets under the direction of Lieutenant Commander H. J. Copeland from USS Nantucket, a training ship of the Massachusetts Nautical School (now the Massachusetts Maritime Academy) that was docked nearby at the playground pier. The cadets ran several blocks toward the accident and entered into the knee-deep flood of molasses to pull out the survivors, while others worked to keep curious onlookers from getting in the way of the rescuers. The Boston Police, the Red Cross, and Army and Navy personnel soon arrived. Some nurses from the Red Cross dove into the molasses, while others tended to the injured, keeping them warm and feeding the exhausted workers. Many of these people worked through the night, and the injured were so numerous that doctors and surgeons set up a makeshift hospital in a nearby building. Rescuers found it difficult to make their way through the syrup to help the victims, and four days elapsed before they stopped searching; many of the dead were so glazed over in molasses that they were hard to recognize. Other victims were swept into Boston Harbor and were found three to four months after the disaster.
In the wake of the accident, 119 residents brought a class-action lawsuit against the United States Industrial Alcohol Company (USIA), which had bought Purity Distilling in 1917. It was one of the first class-action suits in Massachusetts and is considered a milestone in the development of modern corporate regulation. The company claimed that the tank had been blown up by anarchists because some of the alcohol produced was to be used in making munitions, but a court-appointed auditor, Hugh W. Ogden, found USIA responsible after three years of hearings, and the company ultimately paid out $628,000 in damages ($11.7 million in 2025, adjusted for inflation). Relatives of those killed reportedly received around $7,000 per victim (equivalent to $130,000 in 2025).
Cleanup
Cleanup crews used salt water from a fireboat to wash away the molasses and sand to absorb it, and the harbor was brown with molasses until summer. The cleanup in the immediate area took weeks, with several hundred people contributing to the effort, and it took longer to clean the rest of Greater Boston and its suburbs. Rescue workers, cleanup crews, and sight-seers had tracked molasses through the streets and spread it to subway platforms, to the seats inside trains and streetcars, to pay telephone handsets, into homes, and to countless other places. It was reported that "Everything that a Bostonian touched was sticky."
Fatalities
Detail of molasses flood area:
<table><thead><tr><th>Name</th><th>Age</th><th>Occupation</th></tr></thead><tbody><tr><td>Patrick Breen</td><td>44</td><td>Laborer (North End Paving Yard)</td></tr><tr><td>William Brogan</td><td>61</td><td>Teamster</td></tr><tr><td>John Callahan</td><td>43</td><td>Paver (North End Paving Yard)</td></tr><tr><td>Bridget Clougherty</td><td>65</td><td>Homemaker</td></tr><tr><td>Stephen Clougherty</td><td>34</td><td>Unemployed</td></tr><tr><td>Maria Di Stasio</td><td>10</td><td>Child</td></tr><tr><td>William Duffy</td><td>58</td><td>Laborer (North End Paving Yard)</td></tr><tr><td>Peter Francis</td><td>64</td><td>Blacksmith (North End Paving Yard)</td></tr><tr><td>Flaminio Gallerani</td><td>37</td><td>Driver</td></tr><tr><td>Pasquale Iantosca</td><td>10</td><td>Child</td></tr><tr><td>James J. Kenneally</td><td>48</td><td>Laborer (North End Paving Yard)</td></tr><tr><td>Eric Laird</td><td>17</td><td>Teamster</td></tr><tr><td>George Layhe</td><td>38</td><td>Firefighter (Engine 31)</td></tr><tr><td>James Lennon</td><td>64</td><td>Teamster/Motorman</td></tr><tr><td>Ralph Martin</td><td>21</td><td>Driver</td></tr><tr><td>James McMullen</td><td>46</td><td>Foreman, Bay State Express</td></tr><tr><td>Cesar Nicolo</td><td>32</td><td>Expressman</td></tr><tr><td>Thomas Noonan</td><td>43</td><td>Longshoreman</td></tr><tr><td>John M. Seiberlich</td><td>69</td><td>Blacksmith (North End Paving Yard)</td></tr><tr><td>Peter Shaughnessy</td><td>18</td><td>Teamster</td></tr><tr><td>Michael Sinnott</td><td>78</td><td>Messenger</td></tr><tr><td colspan="3"></td></tr></tbody></table>
Causes
Great Molasses Flood
The molasses tank prior to its 1919 rupture—exact date unknown
Several factors might have contributed to the disaster. The first factor is that the tank may have leaked from the very first day that it was filled in 1915. The tank was also poorly constructed and insufficiently tested, and carbon dioxide production may have raised the internal pressure due to fermentation in the tank. Warmer weather the previous day would have assisted in building this pressure, as the air temperature rose from 2 to 41 °F (−17 to 5.0 °C) over that period. The failure occurred from a manhole cover near the base of the tank, and a fatigue crack there possibly grew to the point of criticality.
The tank had been filled to capacity only eight times since it was built a few years previously, putting the walls under an intermittent, cyclical load. Several authors say that the Purity Distilling Company was trying to out-race Prohibition, as the Eighteenth Amendment was ratified the next day (January 16, 1919) and took effect one year later. An inquiry after the disaster revealed that Arthur Jell, USIA's treasurer, neglected basic safety tests while overseeing construction of the tank, such as filling it with water insufficient to check for leaks, and ignored warning signs such as groaning noises each time the tank was filled. He had no architectural or engineering experience. When filled with molasses, the tank leaked so badly that it was painted brown to hide the leakage. Local residents collected leaked molasses for their homes. A 2014 investigation applied modern engineering analysis and found that the steel was half as thick as it should have been for a tank of its size even with the lower standards of the time. Another issue was that the steel lacked manganese, and was more brittle as a result. The tank's rivets were also apparently flawed, and cracks first formed at the rivet holes.
In 2016, a team of scientists and students at Harvard University conducted extensive studies of the disaster, gathering data from many sources, including 1919 newspaper articles, old maps, and weather reports. The student researchers also studied the behavior of cold corn syrup flooding a scale model of the affected neighborhood. The researchers concluded that the reports of the high speed of the flood were credible. Two days before the disaster, warmer molasses had been added to the tank, reducing the viscosity of the fluid. When the tank collapsed, the fluid cooled quickly as it spread, until it reached Boston's winter evening temperatures and the viscosity increased dramatically. The Harvard study concluded that the molasses cooled and thickened quickly as it rushed through the streets, hampering efforts to free victims before they suffocated.
Area today
Great Molasses Flood
Molasses Flood historical marker
USIA did not rebuild the tank. The property formerly occupied by the molasses tank and the North End Paving Company became a yard for the Boston Elevated Railway (predecessor to the Massachusetts Bay Transportation Authority). It is now the site of a city-owned recreational complex, officially named Langone Park, featuring a Little League Baseball field, a playground, and bocce courts. Immediately to the east is the larger Puopolo Park, with additional recreational facilities.
A small plaque at the entrance to Puopolo Park, placed by The Bostonian Society, commemorates the disaster. The plaque, titled "Boston Molasses Flood", reads:
On January 15, 1919, a molasses tank at 529 Commercial Street exploded under pressure, killing 21 people. A 40-foot wave of molasses buckled the elevated railroad tracks, crushed buildings and inundated the neighborhood. Structural defects in the tank combined with unseasonably warm temperatures contributed to the disaster.
The accident has since become a staple of local culture, not only for the damage the flood brought, but also for the sweet smell that filled the North End for decades after the disaster. According to journalist Edwards Park, "The smell of molasses remained for decades a distinctive, unmistakable atmosphere of Boston."
On January 15, 2019, for the 100th anniversary of the event, a ceremony was held in remembrance. Ground-penetrating radar was used to identify the exact location of the tank from 1919. The concrete slab base for the tank remains in place approximately 20 inches (51 cm) below the surface of the baseball diamond at Langone Park. Attendees of the ceremony stood in a circle marking the edge of the tank. The 21 names of those who died in, or as a result of, the flood were read aloud.
Many laws and regulations governing construction were changed as a direct result of the disaster, including requirements for oversight by a licensed architect and civil engineer.
In popular culture
Great Molasses Flood
• The Darkest of the Hillside Thickets' song "Great Molasses Disaster" is about the flood, and their official music video includes many pictures of the aftermath. • Canadian metal band Protest the Hero's song "All Hands" from the album Palimpsest is written from the perspective of a victim of the flood. The piano interlude to the song is titled "Harborside", a reference to the harborside tanks in which the molasses was stored. The last lines of the song references the first hand accounts of the aftermath. • The I Survived children's book series by Lauren Tarshis includes I Survived The Great Molasses Flood, 1919, a story written from the perspective of a 12 year-old girl in Boston. A graphic novel version has also been published. • Bostonian comedian and actress Ayo Edebiri, on Late Night with Seth Meyers, passionately spoke about the Great Molasses Flood where she mentions that she was "reduced to tears" talking about the tragedy, where people outside of Boston are far less aware of the event. • In 2025, a designer card game about the event was announced—"Molassacre: Escape the Flood" was based on the mid-20th century game Mille Bornes.