Ninety years ago today, a 50-foot tall vat of molasses collapsed suddenly in the North End of Boston, sending a 15-foot tidal wave of syrup into the streets. The accident, which took place along the Charles River waterfront just north of Commercial Street, sent more than two million gallons rushing forth at 35 miles per hour, carrying a force of 2 tons per square foot as it washed across the North End Paving Yard. The Boston Post, mixing several culinary metaphors, described the horrific scene the next day.

Like eggshells it crushed the buildings of the North End yard of the city’s paving division… To the north it swirled and wiped out practically all of Boston’s only electric freight terminal. Big steel trolley freight cars were crushed as if eggshells, and their piled-up cargo of boxes and merchandise minced like so much sandwich meat . . . .

The sight that greeted the first of the rescuers on the scene is almost indescribable in words. Molasses, waist deep, covered the street and bubbled about in the wreckage. Here and there struggled a form — whether it was an animal or a human being it was impossible to tell. Only an upheaval, a thrashing about in the sticky mess, showed where any life was. Horses died like so many flies on sticky fly paper.

In the wave of molasses and the vacuum created in its wake, a section of Boston’s elevated train track was destroyed and a train car thrown into the air; several buildings were wrecked, including Firehouse 31, whose collapse trapped a firefighter named George Layhe was trapped underneath the building. Though he managed to keep his head above the molasses for several hours, Layhe eventually lost consciousness and drowned. In the end 21 people lost their lives, crushed or asphyxiated by the most common form of sweetener in the United States at the time. Most were ordinary laborers. Several of the bodies were too battered and glazed to be properly identified. Nearly 200 other Bostonians were injured in the catastrophe. Of the 20 horses that perished in the molasses wave, several had to be shot because they could not be extracted from the goo.

United States Industrial Alcohol, the company that owned the faulty vat, tried to blame the accident on anarchist saboteurs, an accusation that would have been plausible if the tank had not been famously defective to those who lived and worked in its vicinity. Though it was less than four years old when it gave way, the vat had been hastily assembled in 1915 to facilitate the production of industrial alcohol. With the United States escalating it munitions shipments to Britain, Canada and France, USIA and its Boston subsidiary, the Purity Distilling Company, stood to gather enormous profits so long as the war endured; facing competition from major weapons manufacturers like du Pont, Aetna and Hercules, however, USIA needed a tank of its own in Boston, and the ill-fated Commercial Street project was the result.

By 1918, the structure creaked and groaned like a foghorn whenever it was filled, and its leaks were well known to local residents, many of whom sent their children over to scoop up the pools of molasses that drizzled from at least a dozen places along the seams at the base of the structure. Isaac Gonzales, an employee of USIA, had been haunted by nightmares about the tank’s collapse for well over a year. When Gonzales urged his supervisors to do something about the problem, they shrugged off his warnings and insinuated that further complaints might cost him his job.

Litigation over the next several years gave the owners of the molasses facility a wider platform from with to insist that anarchists — Italian immigrants specifically — had instigated the disaster. Though nativist hysteria during those years sowed more than its share of misfortune, liability for the Great Molasses Flood was unmistakable. By 195, USIA had settled lawsuits amounting to more than $600,000.