Marching For King's Dream: 'The task is not done'

Martin Luther King III says today is "not the time for nostalgic commemoration" or "self-congratulatory celebration."

The oldest son of the slain civil rights leader told a crowd at the Lincoln Memorial in Washington that "The journey is not complete. We can and we must do more."

Tens of thousands gathered on the National Mall today to mark the 50th anniversary of the March on Washington and King's famous "I Have a Dream" speech.

Georgia Congressman John Lewis, the only surviving speaker from the 1963 march, railed against a recent Supreme Court decision that effectively erased a key anti-discrimination provision of the Voting Rights Act.

Lewis was a leader of a 1965 march where police beat and gassed marchers who demanded access to voting booths. He says he "gave a little blood on that bridge in Selma, Ala., for the right to vote."

Attorney General Eric Holder praised those who faced repression and brutality to march a half century ago. The nation's first black attorney general said that without them, he'd never be the attorney general and Barack Obama wouldn't be president.