At 12:30 p.m. on January 15, 1919, a steel tank containing 2.3 million gallons of industrial molasses collapsed in Boston’s North End neighborhood. The resulting molasses flood wave, variously estimated at 8 to 15 feet high, moved through the streets at what survivors described as extraordinary speed, demolishing a firehouse, derailing a section of elevated railway, crushing buildings, and drowning 21 people in the molasses flood that Boston’s North End would never forget. One hundred and fifty more were injured.
The company that owned the tank blamed anarchists. It took nearly six years of litigation to prove otherwise.
Why There Was That Much Molasses in Boston
The tank belonged to United States Industrial Alcohol (USIA), and the molasses it held was not destined for rum or baked beans. It was raw material for industrial ethanol, specifically for munitions production. The United States had entered the First World War in 1917, and demand for industrial alcohol was substantial. The tank had been built in 1915 and expanded in 1917 to meet wartime production targets.
Speed of construction was a priority. The war wouldn’t wait. The tank was assembled by a construction company with no prior experience building structures of this scale or type. The steel used was, according to later engineering analysis, too thin for the volume of liquid it was asked to contain. The tank was never tested with water before being filled with molasses, standard practice for storage tanks, then as now, precisely because it catches design failures before they become catastrophic ones.
Local residents had noticed the tank leaked. Children in the North End, then an immigrant neighborhood, primarily Italian, would collect the drippings to bring home. Complaints had been filed with the company. The company’s response, reconstructed from later testimony, was essentially: the tank is fine.
It was not fine.
The Wave
The collapse produced what engineers would later classify as a surge of non-Newtonian fluidA fluid whose viscosity changes under stress or applied force. Unlike water, non-Newtonian fluids like molasses can behave dramatically differently under extreme pressure or sudden release. behavior. Molasses at scale and under sudden release does not behave like water. It behaves like a dense, viscous mass moving with enormous kinetic energyThe energy an object possesses due to its motion. A mass moving at high speed carries kinetic energy proportional to its mass and the square of its velocity, determining its destructive capacity upon impact., fast enough, in this case, to knock buildings off their foundations and fast enough to outrun the people trying to escape it.
Contemporary accounts described a roaring sound followed by a wave that swept through Commercial Street and the surrounding blocks. The city’s Public Works Department had a repair yard nearby; several workers were killed. The elevated railway structure on Atlantic Avenue was visibly twisted. A section of the firehouse at Engine 31 was sheared off. Horses were trapped and had to be shot by police. Recovery of the dead took days; identification was complicated because the molasses coated everything.
Cleanup of the harbor, where the molasses eventually flowed, took months. Some locals maintained for years afterward that the North End smelled faintly sweet on hot days. Historians who have investigated this claim suggest it is probably folk memory rather than fact, but it has proven more durable than almost anything else about the case.
The Company Blamed Anarchists
USIA’s initial response to the disaster was to blame a bomb. January 1919 was a propitious moment for this argument: the war had just ended, anarchist and labor violence was a genuine concern in American cities, and the company had received a letter threatening sabotage. USIA representatives told reporters and investigators that the tank had been deliberately destroyed.
This was, as a legal strategy, audacious. It was also factually unsupported. No evidence of an explosion was found at the site. Engineering analysis of the tank fragments showed structural failure consistent with overpressureExcessive internal pressure that exceeds a structure's design capacity, causing rupture or failure. In tank structures, overpressure can result from material weakness, thermal expansion, or external force accumulation., not a bomb. The anarchist theory had the additional disadvantage of being publicly inspectable: reporters and investigators who went to the scene could look at the tank remains themselves.
The anarchist claim did not survive contact with the evidence. But it bought time, and in 1919, buying time was valuable.
The Molasses Flood Trial
More than 100 plaintiffs brought civil suits against USIA and its parent company, Prohibition-era industrialists with substantial resources and considerable motivation to avoid liability. The cases were consolidated and heard before a court-appointed auditor, a common procedure in complex Massachusetts civil litigation of the period, named Hugh Ogden.
What followed was one of the longest civil proceedings in Massachusetts history. Ogden took testimony from more than 3,000 witnesses over nearly three years. The engineering evidence was contested extensively. USIA maintained throughout that the tank had been structurally sound and that the collapse must have been caused by external factors.
In 1925, nearly six years after the molasses flood disaster, Ogden issued his report. He found that USIA had been negligent. The tank had been inadequately designed, inadequately constructed, and inadequately inspected. The company had received warnings about structural weaknesses and had not acted on them. The collapse was foreseeable. The company was liable.
USIA paid approximately $628,000 in settlements, roughly $11 million in 2024 terms. No company executive faced criminal charges. The construction supervisor who had approved the original tank design had no engineering credentials. That detail did not produce a prosecution.
What Changed Afterward
The molasses disaster is sometimes cited as a turning point in American industrial safety regulation, and the claim has a kernel of truth, though the direct line of causation is harder to establish than popular accounts suggest.
Massachusetts did subsequently strengthen its engineering licensing requirements, and the Ogden report’s detailed findings on the structural failures of the tank contributed to professional engineering standards around large storage vessel design and testing. The requirement that large storage tanks be hydrostatically tested before use, filled with water to check for structural integrity, became more consistently enforced in the years following the disaster.
More broadly, the case established that corporations could be held civilly liable for industrial disasters caused by negligent construction, that “we built it fast and it worked for a few years” was not a sufficient defense when engineers could demonstrate that a competent assessment would have predicted failure. The Ogden report was meticulous precisely because it needed to be: USIA had the resources and the incentive to contest every finding.
The pattern is recognizable. A company builds something under time pressure with inadequate oversight, receives warnings it ignores, and when the structure fails, immediately claims the failure was someone else’s fault. The litigation takes years. The company eventually pays money but admits nothing. The regulatory response is partial and delayed.
This was not the last time this happened.
A Final Note on Speed
The popular claim that molasses “moves slowly” is technically accurate under normal conditions, the phrase “slow as molasses” exists for a reason. What the North End disaster demonstrated is that 2.3 million gallons of the substance released simultaneously under pressure behaves differently from a jar of syrup being poured. Historical accounts give speed estimates ranging from 25 to 35 miles per hour for the initial wave front.
Whether that is precisely accurate is debated. That people could not outrun it is not. The gap between a thing’s ordinary behavior and its behavior under extraordinary conditions is a recurring theme in industrial disasters. The molasses looked inert until it wasn’t.
Twenty-one people died to demonstrate this point. The tank had been telling people something was wrong for years before it did.
Sources
- Wikipedia: Great Molasses Flood , overview with citations to primary sources and contemporary reporting.
- Puleo, Stephen. Dark Tide: The Great Boston Molasses Flood of 1919. Beacon Press, 2003. (The definitive account; draws on trial records and contemporary reporting.)
- Ogden, Hugh W. Auditor’s Report, Dorr et al. v. United States Industrial Alcohol Co., Suffolk Superior Court, Massachusetts (1925). Available via Massachusetts State Archives.
- Park, Edwards. “Without Warning, Molasses in January Surged Over Boston.” Smithsonian Magazine, November 1983.
