Respuesta :
I believe the answer is: Food production
The area in southern states tend to have typically warmer climates that is perfect for wide variety of crops to naturally grow.
This make agricultural plantation in these are become really profitable, and cultural ways to use slave labors started to develop. The northern states on the other hand, tend to be more technologically advance. They do not need manual labour for food production, so they are almost unatached to the use of slave labour.