On March 25, 1911, the Triangle Shirtwaist Factory fire in New York City was one of the deadliest industrial disasters in U.S. history. Management routinely locked doors to stairwells and exits when workers were on shift, to prevent them from taking breaks. So when the building caught fire, many of the workers could not escape the burning building, causing the deaths of 146 garment workers, mostly immigrant women and girls. The tragedy sparked lasting activism for workers’ rights.