Fifty years ago, bigotry was widely accepted. Today, Branch says, even though prejudice is widely denounced, many people unconsciously pre-judge others.
"Unfortunately race in American history has been one area in which Americans kid themselves and pretend to be fair-minded when they really are not," says Branch, whose new book is "The King Years: Historic Moments in the Civil Rights Movement."
Branch believes that today, King would ask people of all backgrounds - not just whites - to deepen their patriotism by leaving their comfort zones, reaching across barriers and learning about different people.
"To remember that we all have to stretch ourselves to build the ties that bind a democracy, which really is the source of our strength," Branch says.