A wave of molasses killed 21 people in Boston at 35 miles an hour

On 15 January 1919, a poorly built steel tank in Boston's North End ruptured and released 2.3 million gallons of molasses in a wave up to 25 feet high, moving fast enough to flatten buildings and kill 21 people. The tank had leaked since it was built, and warm weather had thinned the molasses enough to build fatal pressure. The disaster helped establish modern engineering sign-off requirements for structures.

— Stephen Puleo, Dark Tide: The Great Boston Molasses Flood of 1919 — 2003
Go deeper: get the book →