After two unsuccessful attempts marred by violence, Martin Luther King Jr. led an estimated 3,200 civil rights demonstrators on the historic march from Selma, Alabama to the state’s capital of Montgomery in what would be known as the Alabama Freedom March.

The demonstrators were rallying for equal voting rights for African-Americans, who had been disenfranchised by racist voting laws adopted in many southern states after the Civil War.

In response to the effort, President Lyndon B. Johnson signed the Voting Rights Act of 1965 that August, the legislation which outlaws discriminatory voting practices in the United States.