Slavery was wrong because it denied people basic human rights, and in North America regarding Blacks, it was a cheap way of boosting economic production.
EDIT: I'm quite sure many people know Africans weren't only affected by slavery, yet, that's not the topic of this question. The question is clearly discussing Africans. As for the thumb-down for my answer, whomever did it, note this; because the question only refers to Africans, I answered the question regarding Africans only. Thus, I believe using Blacks as slaves to better the economy for the Southern colonies was cheap, and human because it denied basic human rights. Even if Africans themselves held slaves, I still believe it's wrong. ALL slavery is wrong, no matter the race. No bias here.
To BikerChick: Sounds like your underlying message is 'screw the Blacks, the Chinese did better.' Well, the Chinese and even Blacks have done well in this country, contrary to common belief. Asians only make up 4% of the American population, and that includes ALL East Asians, not just Chinese. Twelve percent of the Asians are poor, so bad situations effect both races. It just seems Black people's problems get the most attention.