History.com: How the Horrific Tragedy of the Triangle Shirtwaist Fire Led to Workplace Safety Laws

The March 25, 1911 Triangle Shirtwaist Fire was one of the deadliest workplace catastrophes in U.S. history, claiming the lives of 146 workers, most of them women immigrants in their teens and twenties. The fire was so horrific it shocked the conscience of New Yorkers and others across the nation and, ultimately, led to changes in safety regulations and more diligent efforts to enforce them. [3:29]