The Tank That Groaned for Four Years

For four years, a steel tank in Boston's North End creaked, leaked, and sweated brown liquid onto the street below. Everyone who lived near it had a theory about why. Nobody with the power to fix it asked.

On the afternoon of January 15, 1919, the temperature in Boston had climbed to an unseasonable 40 degrees Fahrenheit, a thaw after a cold snap. Along Commercial Street in the North End, workers were going about an ordinary winter Wednesday: men unloading freight, families eating lunch in nearby tenements, a crew of city laborers on a break near the waterfront. Above them loomed a structure most of them had learned, over four years of living beside it, to distrust: a steel tank fifty feet tall and ninety feet across, built to hold more than two million gallons of molasses.

At 12:30 p.m., the tank gave way. What followed was one of the strangest industrial disasters in American history — not because a tank failed, but because of how long it had been failing, how many people had noticed, and how completely the company that owned it chose not to listen.

A tank built in a hurry

The tank belonged to the Purity Distilling Company, a subsidiary of United States Industrial Alcohol (USIA). It went up in 1915, on a stretch of waterfront land at 529 Commercial Street, to receive molasses shipped up from the Caribbean. The molasses wasn’t primarily destined for kitchens. USIA distilled it into industrial alcohol, and in 1915 there were two booming markets for that alcohol: munitions manufacturers supplying the war raging in Europe, which needed it to produce explosives, and distillers who wanted to get as much product out the door as they could before Prohibition — then visibly approaching — shut the alcohol business down. Demand was high and USIA wanted the tank built fast.

It was. According to the account later compiled from the engineering investigation, the company’s construction process skipped basic safeguards that would be considered non-negotiable today: there was no independent structural review, the steel plates were undersized for the loads they’d eventually carry, and the man overseeing construction, assistant treasurer Arthur P. Jell, had no training in engineering and reportedly could not read a blueprint. The tank was tested for leaks by filling it with a few feet of water — nothing close to a full load of molasses — before being declared ready.

Almost immediately, residents of the North End noticed something was wrong. The tank leaked. Neighborhood children were known to scrape congealed molasses off its sides and eat it. The structure groaned audibly when it was full, loud enough that some residents said they could hear it creak from inside their homes. According to multiple historical accounts, a company employee named Isaac Gonzales raised concerns about the tank’s condition directly to Jell. The response, as the story has been told since, was not an inspection or a repair. It was a paint job: USIA had the tank painted brown, the same color as molasses, so the leaks would be less visible.

For four years, the tank held. It also kept leaking, kept groaning, and kept being refilled.

The afternoon it let go

On January 15, 1919, the tank had recently taken on a fresh shipment, bringing it close to its full capacity — historical estimates put the volume at the time of collapse at somewhere between 2.1 and 2.3 million gallons of molasses, with sources differing slightly on the exact figure. The unusually warm afternoon, after a stretch of cold weather, is thought to have added stress: the molasses inside had likely partially frozen and then begun to warm and expand, adding pressure to a structure already strained past what it was built to hold.

Witnesses described a sound like machine-gun fire, which turned out to be the rivets popping out of the tank’s steel plates in rapid succession, and then a deep rumble as the tank’s walls tore open. A wave of molasses, by some estimates reaching heights of 25 feet near the tank and moving at an estimated 35 miles per hour, exploded outward across Commercial Street.

It behaved like almost nothing else people had seen a flood do. Unlike water, which spreads and drains, the molasses was dense and viscous. The force of the collapse drove sections of the tank’s steel plating into the girders supporting the Boston Elevated Railway line that ran above Commercial Street, and part of the elevated structure came down. A train had been due to pass along that stretch of track within moments of the collapse. According to an account from the Massachusetts Secretary of the Commonwealth’s office, one of the line’s car operators — identified there as Royal Albert Liman — realized the rails ahead had vanished into the wreckage and acted fast enough to stop oncoming cars before they ran into the gap; other retellings describe a motorman sprinting to the rear of his own train and reversing it off the compromised section just in time. The exact sequence varies slightly between sources, but all agree on the outcome: a derailment into the flood, which could easily have added many more deaths, was averted by seconds and one person’s quick reaction.

Elsewhere, the wave was less forgiving. It swept away buildings, carts, horses, and people, burying some where they stood and dragging others for blocks. It flattened the Engine 31 firehouse on Commercial Street, trapping several firefighters inside the collapsed structure. Nearby, workers eating lunch at a city-owned paving yard — many of them municipal employees on their break — were caught directly in the wave’s path, which is why public employees made up a disproportionate share of the dead. Reports from the time also describe horses struggling and dying in the molasses, unable to free their legs from the thickening muck.

Then, almost as cruelly, the flood stopped moving and began to set. As the molasses cooled in the January air, it thickened into a dense, sticky mass that trapped survivors in place and made the work of digging out victims and bodies agonizingly slow. Accounts of the rescue describe people effectively glued to the ground if they stood still in it for even a minute, and rescuers themselves struggling to move through it to reach the trapped. Police and firefighters were joined by Red Cross volunteers and cadets from the nearby training ship USS Nantucket, moored at the Charlestown Navy Yard, who waded into the muck to pull out survivors; some victims they could hear calling for help but could not reach in time.

Twenty-one people died, most from drowning in molasses, being crushed by debris, or suffocating; about 150 more were injured. Among the dead were city paving-department workers, a truck driver, a firefighter, and residents of the tenements along the waterfront, including children as young as ten. It remains one of the deadliest industrial accidents in Boston’s history, and bodies continued to be recovered from the harbor and the wreckage for days afterward.

Cleanup, and a city stained brown

In the aftermath, the physical cleanup took months. Workers tried everything from sand to pumping salt water from the harbor onto the hardened molasses, eventually discovering that seawater broke it down more effectively than fresh water. The harbor itself reportedly ran brown with molasses until summer. Rescue and cleanup crews, along with volunteers from the Red Cross and the Navy, worked for weeks just to clear streets and recover the dead. Reports from the time describe the North End’s buildings, streetcars, and even the harbor’s surface as stained for months afterward — residents said that everything downtown, doorknobs and telephone receivers included, felt sticky for the rest of that winter.

USIA’s first public response was not to accept responsibility. The company suggested that the tank had been destroyed by a bomb, blaming anarchists — a politically convenient theory in 1919, a year of real anarchist bombings elsewhere in the country, including one that would hit Attorney General A. Mitchell Palmer’s own home in Washington, D.C., just four months later. It was a plausible-sounding story for the era, and for a while it was taken seriously.

What the courts found

More than 100 lawsuits were eventually consolidated into a single class-action case against USIA, representing victims’ families and property owners. Because Massachusetts law at the time didn’t allow jury trials for cases this complex against a single corporate defendant, the case instead went before a court-appointed auditor, Boston attorney Hugh W. Ogden, who held hearings and took testimony for roughly six years before issuing his findings.

Ogden’s 1925 report demolished the sabotage theory and instead laid the blame squarely on the tank’s construction. His investigation found the tank had been poorly designed and built, with steel too thin to safely hold the loads it was meant to carry, and that the company had ignored warning signs — the leaks, the groaning, the concerns raised by its own employees — for years. USIA was found liable and ultimately paid an estimated $628,000 in settlements to victims and their families, a substantial sum for the period, though it came only after years of delay for people who had lost homes, limbs, or relatives.

The case had consequences beyond the settlement checks. It became one of the early examples cited in the development of stricter engineering standards and building codes in Massachusetts and, more broadly, in the United States — part of a shift toward requiring calculations to be checked and stamped by qualified, licensed engineers, rather than trusted to the judgment of company officers with no technical training. Massachusetts subsequently moved to require that architects’ and engineers’ structural plans be signed off on by a registered professional and, for large tanks and similar structures, independently verified. Some histories of American civil engineering point to the Boston molasses disaster, alongside a handful of other early 20th-century structural failures, as a turning point in how seriously regulators began taking industrial construction oversight — a shift that outlived Prohibition itself. By the time USIA’s legal battle finally concluded in 1925, the alcohol market the company had rushed to serve was gone: national Prohibition had taken effect in January 1920, a year after the flood, closing off the very demand the tank had been built in a hurry to meet.

What’s left of it now

The tank itself was removed, and for decades the site at 529 Commercial Street served other industrial and recreational purposes — at one point hosting a baseball diamond used by local Little League teams, and later becoming home to a public recreation complex. Today a small plaque near Puopolo Park marks the site, noting the disaster and its date.

A piece of local folklore has persisted for over a century: that on unusually hot summer days, people in the North End can still smell a faint sweetness drifting up from the pavement near the old site — the ghost of two million gallons of molasses that never fully washed away. It’s a charming story, and it shows up in nearly every retrospective written about the disaster, but it should be read as neighborhood legend rather than documented fact; no scientific or contemporaneous source confirms it, and it’s presented in local history pieces explicitly as something residents say, not something anyone has measured.