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

The Attica Prison Riot, also known as the Attica Prison Rebellion, the Attica Uprising, or the Attica Prison Massacre, took place at the state prison in Attica, New York; it started on September 9, 1971, and ended on September 13 with the highest number of fatalities in the history of United States prison uprisings. Of the 43 men who died, 33 inmates and 10 correctional officers and employees, 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 uprising. The Attica Uprising is one of the best-known and most significant events of the prisoners' rights movement.Prisoners revolted to seek better living conditions and political rights, in their words, to be treated like men and not beasts. On September 9, 1971, 1,281 of the approximately 2,200 men incarcerated in the Attica Correctional Facility rioted and took control of the prison, taking 42 staff hostage. During the following four days of negotiations, authorities agreed to 28 of the prisoners' demands but would not agree to demands for the removal of Attica's superintendent nor to complete amnesty from criminal prosecution for inmates for the prison takeover. By order of Governor Nelson Rockefeller (after consultation with President Richard M. Nixon), armed corrections officers and state and local police were sent in to regain control of the prison. By the time they stopped firing, at least 43 people were dead, 10 hostage correctional officers and civilian employees and 33 inmates, nearly all killed by law enforcement gunfire.Rockefeller had refused to go to the prison or meet with prisoners. After the uprising was suppressed, he said that the prisoners "carried out the cold-blood killings they had threatened from the outset". In fact, medical examiners shortly confirmed that all but the deaths of one officer and three inmates were caused by law enforcement gunfire. The New York Times writer Fred Ferretti said the rebellion concluded in "mass deaths that four days of taut negotiations had sought to avert".As a result of the rebellion, the New York Corrections Department made changes in prisons to satisfy some of the prisoners' demands, reduce tension in the system, and prevent such incidents in the future. While there were improvements to prison conditions in the years immediately following the uprising, many of these improvements were reversed in the 1980s and 1990s. Attica remains one the most infamous prison riots to have occurred in the United States.