There wasn't much cheap land left, what there was, was mostly in Texas so there is some room there. By the 1860s the Southeast was already pretty much settled. ......
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Topography divided the Old South into three (or more) regions with distinct economies.
Tide water saw plenty of fishing and shipping.
Those ships served plantation that owned the best bottom land.
The best bottom land produced agricultural surpluses that could be sold overseas in exchange for foreign-made tools and luxuries. Most slaves worked lucrative bottom lands.
Finally, rugged, mountainous lands had soil too thin for extensive farming. They were inhabited by late Scots-Irish immigrants who moved farther and farther up "hollers" in search of small patches of fertile land barely big enough for kitchen gardens. These "hillbillies" and "white trash" were poor, semi-skilled, recent immigrants who had to resort to hunting, fishing, moonshining, etc. to eke out a living.
The few free blacks who moved to mountainous parts of the Old South also struggled to fish, hunt and garden enough food to feed their families.
There were few slaves in "them thar hills" because the soil was too poor to support large corn or tobacco or cotton plantations.
Industrializing the Old South would start with trade embargoes, then "rice mining" and finally small, water-powered factories along up-country rivers. Those small factories would start building agricultural tools.
Second generation, large factories would be coal-powered and produce rails and rolling stock.
As factories became more sophisticated, literacy became more important, while slaves declined in value.
"The term "rice mining" originated during the Meiji Restoration when rice farmers starved to feed new factory workers. Joseph Stalin starved Ukrainian farmers to pay for industrializing the (new) Soviet Union. Mao Tse Tung imposed similar misery on Chinese peasants. Hitler worked slave labourers to death to prop up his overly ambitious Third Reich .... but slaves only helped Hitler for a few years.
In conclusion, you can shift assets from farms to factories, but "rice mining" is a painful process and not practical in a democracy.