Historian Isabel Wilkerson: Charlottesville is a wake-up call

The events in Charlottesville, VA, this weekend left the nation wondering: How could this happen in 2017? Isabel Wilkerson, author of "The Warmth of Other Suns," joins Lawrence O'Donnell to discuss the racist undercurrent that's been with the U.S. since its birth.Aug. 15, 2017