I watched "Raisin in the Sun", and was pleasantly surprised at how racism was portrayed in its raw state, and allowed to be shown for the ugliness that it is. I'm curious which movies people found the most honest and truthful about its experience, without becoming preachy about it. The point isn't to minimize the importance of the topic, but rather I find movies which just put ugliness on full uncensored display can often be far more powerful than those which attempt to cleanly address inherently dark topics. Hopefully this description does my request justice. "The Long Walk Home" is also one of my favorites on this topic.
Edit: To be clear, I'm not looking for movies which some people find to be racist due to modern interpretations. I'm looking for movies which even at the time they were made were clearly meant to demonstrate racism. Thanks!