From NBC News today:

Thousands of people in Alabama will cross the Edmund Pettus Bridge from Selma into Montgomery on Sunday to recreate a pivotal moment in the civil rights movement on its 52nd anniversary. On March 7, 1965, images of police beating and throwing tear gas at 600 marchers flashed across television screens nationwide, capturing what is now known as “Bloody Sunday.”

You might be interested in The Best Resources For Teaching About Selma.