SELMA, Ala. -- March 7, 1965, will forever be etched in American history as "Bloody Sunday."
On that fateful day, 600 civil rights activists gathered in Selma, Alabama, to begin a 52-mile march to the state's capital, Montgomery.
Led by future Congressman John Lewis and Hosea Williams, the peaceful demonstrators demanded an end to discrimination in voter registration, particularly for Black southerners.
While the 1870 ratification of the 15th Amendment granted African Americans the right to vote, repressive and discriminatory state and local laws -- like poll taxes, literacy tests and other voter suppression tactics -- kept them away from the ballot boxes in the Jim Crow South.
As the crowd attempted to cross the Edmund Pettus Bridge, they were confronted by white Alabama state troopers who violently attacked them with billy clubs and tear gas.
Seventeen people were hospitalized and dozens more injured by police, including Lewis, who suffered a fractured skull.
Televised images of the violence sent shockwaves throughout the country and helped put pressure on politicians to act against discrimination at the polls.
One week after Bloody Sunday, President Lyndon B. Johnson introduced the Voting Rights Act of 1965 to prohibit race-based discrimination in voting.
"What happened in Selma is part of a far larger movement which reaches into every section and State of America," Johnson said in an address. "It is the effort of American Negroes to secure for themselves the full blessings of American life. Their cause must be our cause too. Because it is not just Negroes, but really it is all of us, who must overcome the crippling legacy of bigotry and injustice. And we shall overcome."
Johnson signed the Voting Rights Bill into law on Aug. 6, 1965, with Dr. Martin Luther King, Jr. and other civil rights leaders attending the ceremony.
After the signing, the majority of the Black electorate in Southern states were able to vote for the first time in American history.
In 2013, the U.S. Supreme Court gutted a portion of the 1965 law that required certain states with a history of discrimination in voting, mainly in the South, to get U.S. Justice Department approval before changing the way they hold elections.
The supporters of the end of preclearance said the requirement -- while necessary in the 1960s -- was no longer needed. Voting rights activists have warned the end of preclearance is emboldening states to pass a new wave of voting restrictions.
On Sunday, Vice President Kamala Harris spoke in Selma at an event marking the 57th anniversary of "Bloody Sunday." Harris is the first female U.S. vice president and the first Black woman and person of South Asian descent in the role.
The Associated Press contributed to this report.