I'm just going to take this opportunity to plug
The Half Has Never Been Told. You've probably read it and/or know the story from other sources, but that book transformed my understanding of antebellum US economic history and the role slaves played in it, so I'll talk about it briefly.
Before I read it, I was under the impression that slavery was an archaic, preindustrial mode of production that was economically inferior to wage labor. I was wrong - using slaves to farm labor-intensive cash crop monocultures (cotton, sugar) made perfect economic sense and people really could be beaten into producing higher yields; the level of cotton production in the 1850s would not be seen again until mechanization, artificial fertilizer, and pesticides in the mid-20th century. Textiles were the biggest industry during the first industrial revolution in both the North and the UK, and they depended on the enormous levels of cotton production from the South. The result is that slavery was a critical and tightly-integrated part of the early industrial economy, even as the Yankees and Brits pretended to be morally superior for not using it themselves.
The belief that it was inherently inefficient was common among Northern abolitionists at the time, but this was mistaken - brutal as it was, it was quite efficient. That belief had also been common among the "enlightened" types earlier, in the first couple decades of US history. One of the justifications Jefferson would use was that he might be dependent on it, but the overall trend is that slavery is fairly inefficient and was slowly being phased out. This is what happened in the North, but intensive farming of cotton following the cotton gin changed the equation and made it immensely profitable. In Maryland and Virginia, the climate was too cold for cotton, and tobacco prices were permanently low, but there was one very valuable cash crop they could grow: slaves, whose price had skyrocketed. The Deep South had an economy based on slave labor in cotton plantations, the upper South had an economy based on selling them slaves, and the North had an economy based in large part on the textiles that could be spun out of the slave-produced cotton.
I was a little surprised by how modern the arguments for keeping slavery sounded. They were basically property-rights arguments that could have come out of the mouth of a conservative or libertarian today, except that the property was human. A modern libertarian would say that the humanity of the property is the fundamental distinction that makes slavery a very un-libertarian institution. They're not totally wrong, but I don't think the difference really is that fundamental in a world where "freedom" for a wage laborer essentially means the freedom to be homeless and/or starve. Another major argument was that slavery was the core of the entire Southern economy, so it could never be abandoned, an argument familiar today when you read of the economic necessity of fossil fuels, sweatshops, factory farming, etc. I knew of that argument ahead of time but did not grasp the parallels until I read that book.
The best part was the financial shenanigans. The bubble that led to the Panic of 1837 was fueled by land and slave speculation, including slave mortgages and slave mortgage-backed securities. It was illegal to own and keep a slave in New York, but it was perfectly legal to buy the mortgage someone took out on the slave, bundle that together with other slave mortgages, and sell it on as an early version of the mortgage-backed securities that caused the Panic of 2008. Of course it all fell apart, and the ensuing depression lasted for years, not helped by the way Jackson had gone full Ron Paul on the Second Bank of the United States. Other firms, such as Lehman Brothers, got their start in the recovery and new boom that followed in the 1840s and 1850s.
