I'll expand on a point I made earlier. Without slavery, we have no significant African American population. Those people wouldn't even exist because their ancestors would have never met, thus they would have never been born.
If I were forced to get into a time machine that would make me a person born in 1830, if I could, I would choose to be born a slave over a poor white from that era. This is not a defense of slavery, I wish there had never been slavery in the new world. How awesome would this country be if our black population was under 1% instead of around 15%. Memphis might actually be a nice city, and Atlanta wouldn't have to keep growing because there would be no need for all those people to keep moving away from the bad parts of town.