As the plantation owners got more consolidated and bought each other out, they became better and better at forcing more and more labor and profits from the plantation slavery system. Just like how corporations are making bigger and bigger profits today.
Like all corporations, the plantation owners learned just how little they needed to force the people they were allowed to abuse to do more work. They got more and more out of the slaves with less food, less shelter, less managers and overseers. So much so that plantation owners left the South and lived in the big cities of the North. Just like today how pay and wages never keep up with inflation and corporations pay less and less to their workers. All the while the filthy rich owners live in high price cities, not near their very polluting factories or plants.
The governments of the South took on a lot of what plantation owners use to do. The state hunted down escaped slaves with militias and bounties. They put up laws to prevent owners from freeing their slaves on death. A common practice to obtain God's forgiveness, just in case the bible was wrong about owning people. Just like today how the government doesn't raise the federal minimum wage so corporations don't have to pay more. And how the government doubles Social Security and Medicare taxes of anyone who wants to start their own business. Keeping competition against corporate control to an all time low.
Yup, just more of the same old same old.