The USA only had slavery for 80 something years before we ended it, and we ended it nearly world wide when we did..
If anything we are more responsible for ending slavery than any other nation and practiced it for far less time than most every other nation..

If we are so terrible, then why do all the 3rd worlders want to move here, and why are "minorities" not leaving the country?
Eh?

Maybe because it doesn't matter who you are or where you are from, the USA has the most opportunity to be had by anyone in the world, and it is truly available to all that are here or come here legally...
You just gotta put on your bigboy pants and go and get it..