In 1810, why did so many african americans (3/4 out of 2 million) that lived in the united states live in the south?

(Also if all your going to do is tell me to "look through my text or whatever don't bother. Think about it, if the text explained it clearly (spoiler alert; it didn't) why would I be on here?)

Where were the vast majority of plantations at that time?

Ahhhh I think I got it. Would the answer be because thats where most of the plantations were, so since the majority of african americans at the time were slaves, they all lived where they could work?

Thanks!