A locked exit door turned a factory fire into 146 deaths — and rewrote US labor law

On 25 March 1911, fire broke out on the top floors of the Triangle Shirtwaist Factory in Manhattan, where managers had locked stairwell doors to stop workers taking breaks. 146 workers, mostly young immigrant women, died, many jumping from ninth-floor windows. Public outrage drove sweeping new fire-safety and labor laws across New York State within two years.

— Wikipedia contributors, Triangle Shirtwaist Factory fire — 25 March 1911