It had to do with the earliest days of British colonies in the United States as being mercantilistic enterprises which, among many other things, placed a priority on resource extraction as a means to generate wealth through trade and/or manufacture in the mother country. The south was prime for harvesting valuable resources (cotton, tobacco) on a large scale that generated large profits. That's not to say the north was poor or lacked resources but thrived on an assortment of businesses that facilitated the central ideal of colonial trade. Over time, from the founding of the country up until the Civil War, industrialization and capitalism slowly took hold as prominent ideas in the north. That wasn't so for the south. Perhaps, it was a little, "if it's not broke, don't fix it," mentality. Either way, they stuck to the economic model that had worked for them and they had generously profited from for so many years. Retrospectively, we can say that they didn't see the tide changing and suffered for it during and after the Civil War, but that's really neither here nor there.