This is a well-understood topic in basic economics. Citizens and Consumers are v

This is a well-understood topic in basic economics. Citizens and Consumers are vastly cheaper and more productive than slaves. Worse, farm machinery is vastly cheaper than employees or slaves. If slavery was necessary rather than counter-productive it wouldn’t have gradually disappeared with industrialization. It did. Over the next century from 1860 to 1960 we moved from ~70 of the workforce in farming to 10% to 2%. Finally, trade policy from other states would have prohibited use of slaves in production. It was a pointless slaughter of more Americans than the total number of slaves ever imported to the States. We had a dead American for every slave imported.