Positive; Generated economy for the south, made large plantation owners rich, help pave the way for the industrial revolution by placing a demand on clothing production, and the price of slaves was raised.
Negative; Small farms in south remained poor, more land owned by a single plantation owner (could be positive or negative), plantation owners needed more slaves (could be positive or negative), less variety of cash crops growing in the south (mostly cotton being produced)
I hope this helps :)
