The March 25, 1911, blaze, which killed 146 people (most of them women), prompted public outrage and led to the immediate passage of fire safety legislation and became a rallying cry for labor reforms.

The Triangle Shirtwaist Factory occupied the top three floors of a Manhattan office building. It was one of the most successful garment factories in New York City, employing some 1,000 workers, mostly immigrant women. But the conditions were hazardous: The space was cramped, accessible only via stairwells and hallways so narrow that people had to pass single-file; only one of the four elevators was regularly in service; the cutting machines in the workroom were gas-powered; scraps of fabric littered the work areas; the water barrels (for use in case of fire) were not kept full; and the no-smoking rule was not strictly enforced. In short, it was an accident waiting to happen.

When the fire broke out on a weekend (the cause is unknown since the building was charred so badly), about half of the employees were there. Smoke and fire, however, were not the only causes of death: In the panicked escape, people were trampled, fell in elevator shafts, jumped several stories to the pavement below, and were killed when a fire escape melted and collapsed.

While the fire happened during a time of labor reform, those reforms had not come soon enough to save the lives of the Triangle Shirtwaist Factory employees, who had been subjected to extremely poor and dangerous working conditions. The disaster became a rallying cry for the labor movement: Tens of thousands of people marched in New York City in tribute to those who had died, calling attention to the grave social problems of the day.

In New York State, the fire safety reforms for factories came right away: The legislature appointed investigative commissions to examine factories statewide, and 30 ordinances in New York City were enacted to enforce fire prevention measures. One of the earliest was the Sullivan-Hoey Fire Prevention Law of October 1911, which combined six agencies to form an efficient fire commission. Soon factories were required to install sprinkler systems.

The Triangle Shirtwaist Factory fire became an object lesson for the entire nation, prompting the consolidation of reform efforts. The much-needed labor reforms, which addressed the miserable working conditions, did not come until years later.