One more thing: the documentary series “Eyes on the Prize” is excellent. It shows period video of all the major moments in the history of the Civil Rights Movement. I notice that it is viewable on YouTube. Yes, you can tell occasionally that it was made by mainline Democrats of the 1980s variety, but still, it’s probably the place to start.
I think the most important figure in the fight for black rights in the 20th century was Thurgood Marshall. I’ve assigned both Williams’ biography of Marshall and the first volume of Tushnet’s 2-volume version, Making Civil Rights Law. Williams isn’t an attorney, and he sometimes flubs the law. Tushnet is a Red, so ditto. Marshall was generally an awful Supreme Court justice, but he was a momentous attorney–the most important American attorney of the 20th century. Tushnet captures that.