The basic fact was never in dispute: on February 26, 2012 George Zimmerman shot and killed 17-year-old Trayvon Martin in the town of Sanford, Florida. When a verdict of “not guilty” was announced, African Americans saw the outcome as another painful link in a chain of unpunished cruelty dating back hundreds of years. This month historian Hasan Kwame Jeffries examines the long history of racial violence in America and how the issue of race permeated every aspect of the tragedy from the shooting, to the reluctance of the local police to arrest Zimmerman, to the conduct of the trial itself. Read more here.