Actually the opposite. Social and political institutions of the slave owning South had developed an entrenched extractive hierarchy not unlike the aristocracies of Eastern Europe at the time. The legacy of these oppressive institutions has lead enterprising Americans to seek their fortunes elsewhere throughout history.

Yes I believe in Ken Burn's documentary he mentioned that even at the time the North's economy far dwarfed the South's. Especially in terms of technological advancement.

Without slavery, much of the colonization of the US would have been economically pointless. Without slavery, much of the non-slaveholding US (and England) would have had little incentive to industrialize.

While it's true that there is a bit of incumbent/disruption element involved - the American south was probably the most advanced agricultural civilization ever, while the north invested heavily in the very disruptive industrial revolution - I'd say having broad swaths of their entire society burnt to the ground and then effectively confiscated by Northerners has much more to do with any present-day economic troubles.

Not to say they didn't deserve it, but the entire American south basically had to reboot. Some states figured it out (Virginia, North Carolina, Georgia), and others haven't done as well (Mississippi, Alabama, Tennessee).

> the [antebellum] American south was probably the most advanced agriculture civilization ever

I don't follow. Certainly the current farming system in the American mid-west is orders of magnitude more productive. But even if we're focussed on pre-industrial history, are you sure that the ancient South American agri-economies weren't better? And for productive land use, what about Japan and south-east Asia, where every square inch ran like clockwork.

I'd like to see a citation for that. Everything that I've read up to an undergraduate level implied that their farming methods were less than ideal, even by the standards of the day, and that in many ways prime land had been exhausted.

Tennessee originally wanted to fight for the North and much of Western North Carolina didn't want to join the confederacy because most of the people in these regions owned no slaves and were rather poor Irish, Scottish, etc. immigrants rather than aristocracies and industrial tycoons like a lot of the Deep South and didn't see any benefit to supporting slavery. However, they did always wonder what'd happen if they didn't join the rich Southerners and the union lost. There's a lot more factors obviously but lumping in Appalachia with the south is an oversight that is pretty misplaced.

Tennessee and much of Appalachia has been historically on the side against slavery and corporate interests until somewhere around 60 years ago. I don't know how it happened besides hand-waving "Southern Strategy."