All my life I had just assumed that the racial segregation we see in inner city communities was a "natural" occurrence. What a naive schmuck I was. The Color of Law: A Forgotten History of How Our Government Segregated America has opened my eyes to how it was mostly government policy that has created what we now call ghettos/slums etc.
The book is infuriating. Law after law, policy after policy made it difficult for African Americans to own homes near their workplaces even where they used to work side by side with whites. From straight up federal mortgage guarantees that only applied for whites, to the more indirect "looking the other way" law enforcement when racists caused trouble for blacks who found a way to move into "white" neighbourhoods, this book details the systemic racism that has led to today's segregation.
The book also makes a good legal case for why the US Constitution requires rectifying this problem, based on case law and the written opinions of Supreme Court judges.
The book was a bit on the dry side though, so I only recommend it if you are interested in this topic.