TOPSHOTS Police watch over a crowd on Broad Street before an event at the Edmund Pettus Bridge on March 7, 2015 in Selma, Alabama. US President Barack Obama and the first family will visit Selma to commemorate the 50th anniversary of Bloody Sunday, when civil rights marchers attempting to walk to the Alabama capital of Montgomery to end voting discrimination against African Americans clashed with police. AFP PHOTO/BRENDAN SMIALOWSKI