U.S. President Barack Obama (C, in white shirt, back to camera) talks to participants after a commemorative march across the Edmund Pettus Bridge in Selma, Alabama, March 7, 2015. The event comes on the 50th anniversary of the 'Bloody Sunday' march at the bridge, where police and state troopers beat and used tear gas against peaceful marchers who were advocating against racial discrimination at the voting booth. REUTERS/Jonathan Ernst (UNITED STATES - Tags: POLITICS ANNIVERSARY SOCIETY)