Also in the Caribbean it was seen as more economical to work the slaves to death and then import new ones. The conditions on those plantations made south Carolina look like Disney land and the average life expectancy was only a couple years.

In the American south there was more emphasis on keeping the slaves alive and "breeding" them to get more slaves instead of importing more.

This is also why the African diaspora population is a bit less in the Caribbean then in America even though way more Africans were brought into the Caribbean, most of them died before they could have children.