On March 25, 1911, fire tore through the Triangle Shirtwaist Factory in New York, killing 146 workers in under 30 minutes.
Most were young immigrant women, trapped by a locked ninth-floor door and a collapsing fire escape.
The outrage forced sweeping safety laws — fire escapes, unlocked doors, real inspections.
The whole disaster traced to one detail: a stairway door locked to stop theft. Its owners were tried for manslaughter — and acquitted.