I was actually citing the economic interests and political actions in support of the same, of the period, not necessarily advocating either one. For that matter, I support, retroactively, the Southern position more often than not, on grounds of constitutionality, principle and moral logic. As far as free trade goes, my view on that is somewhat akin to my view on peace - it's all every well and good, and a preferable state of affairs, but only if the other guy plays along. In a world where China exists, let alone is our primary trade partner, free trade is something akin to suicide. Also, we don't have free trade, we have bureaucracies masquerading as free trade organizations.
IDK why. It's pretty much taken as axiomatic that free labor out-produces and out-performs compulsory labor, particularly in the long term. Slavery died a natural death in the north. No one, especially not the author of the article, would assert some sort of widespread morality to its confinement in a single region, when at one point it was legal throughout the country. It fell out of use, and allowed the moralists to obtain de jure prohibition of the practice, because other methods of obtaining labor were more productive. The South constantly sought the extension of legal slavery, and in the early 19th century, the issue of each state's joining the union as slave or free was fiercely contested, as the South sought to maintain equal numbers so as to prevent the free states from gaining a majority in the Senate. If slavery was a more viable or successful policy, they would not need to agitate for it, and it lacks the moral impulse of abolition.
And again, that's not something unique to the human race. On a personal level, it's something akin to feeling guilt for original sin.

I have no problem discussing the issues of pride and guilt from a non-reparations perspective... but this is not that discussion, is it?
Not to mention, the parts of Virginia where they mined coal are now probably in WEST Virginia, a state that seceded from Virginia at the start of the Civil War with abolition in its Constitution.
Chesterton and Belloc referred to that sort of employment as "wage-slavery" when advocating distributionism. My point about manufacturing was that slaves were absent from the industries that have contributed much more prominently to the enrichment of America than cotton or indigo plantations.