Updated at 6:30 p.m. EDT

A day after President Obama spoke in Selma, Ala., to mark the 50th anniversary of 'Bloody Sunday' — a police crackdown on the 1965 voting rights march — tens of thousands of people gathered to trace the footsteps of the original protesters who were met by state troopers firing tear-gas and swinging truncheons at the foot of the Edmund Pettus bridge.

The march started ahead of schedule, Reuters reports, with a large throng of people proceeding across the bridge before dignitaries were brought to the front to lead them.

Those assembled in Selma, which was the starting point for a series of marches to Montgomery in 1965 aimed at securing voting equality for blacks in the South, also honored the late President Lyndon Johnson, who pushed the 1965 Voting Rights Act through Congress.

The Associated Press reports:

"Luci Baines Johnson accepted the award Sunday from Selma city officials on behalf of her father, saying it meant so much to her a half century later to see him honored for the landmark act."'You remember how deeply Daddy cared about social justice and how hard he worked to make it happen,' she told the crowd. Several hundred gave her a standing ovation and some chanted, 'L.B.J., L.B.J.'"

Addressing a crowd in Selma on Saturday, Obama said the events of March 1965 crystalized a "turbulent history" of slavery, civil war, segregation, Jim Crow and the dream of the Rev. Martin Luther King, Jr.

He said that even today, "there are laws across this country designed to make it harder for people to vote.

"As we speak, more of such laws are being proposed. Meanwhile, the Voting Rights Act, the culmination of so much blood and sweat and tears, the product of so much sacrifice in the face of wanton violence, stands weakened, its future subject to partisan rancor," the president said to the crowd, which included former President George W. Bush, former First Lady Laura Bush and about 100 members of Congress, all Democrats.

The Rev. Al Sharpton, speaking at Sunday's unity breakfast, echoed Obama's concern in an apparent reference to the U.S. Supreme Court's 2013 decision striking down a requirement contained in the law that would require states with a history of voter suppression to get approval from the Department of Justice before changing their voting laws.

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