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President Barack Obama speaks at the Let Freedom Ring ceremony at the Lincoln Memorial in Washington, Wednesday, Aug. 28, 2013, to commemorate the 50th anniversary of the 1963 March on Washington for Jobs and Freedom. It was 50 years ago today when Martin Luther King Jr. delivered his "I Have a Dream" speech from the steps of the memorial. (AP Photo/Carolyn Kaster)

Marchers mark 50 years since King's 'Dream' speech

Thousands of marchers gathered on Washington's national mall on Wednesday to commemorate civil rights leader Martin Luther King's famous "I have a dream" speech 50 years ago as activists said his goal of racial harmony remains elusive. (Reuters)