The four-day Attica Prison riot begins, eventually resulting in 39 dead, most killed by state troopers retaking the prison.

The Attica Prison riot took place at the Attica Correctional Facility state prison in Attica, New York. The riot started on September 9, 1971, with a violent takeover of the prison control center in which one prison officer, William Quinn, was killed. It ended on September 13 with the highest number of fatalities in the history of United States prison riots. Of the 43 men who died, all but one guard and three inmates were killed by law enforcement gunfire when the state retook control of the prison on the final day of the riot. The Attica riot has been described as a historic event in the prisoners' rights movement.