The US represents a certain mythology around the Enlightenment principles that were most popular at its founding: one of the big ones was Bentham/Smith utilitarian market thinking, resulting in a conflation between "pursuit of happiness" and "pursuit of property" that the founders were not exactly encouraging of, but which many contemporary authors, inspired by John Locke's writings on property, were considering.
I believe that's at the heart of the Civil War discussion, because downstream of that mythology, alongside the "life and liberty" parts, are the compromises of slave vs free states. What took place from the founding into the 19th century was the experiment in following the myth and seeing where it led, which favored industrialization. The South had the wealth when the nation was agrarian, but the founding principles gave a political edge to industrialists, enabling the development of roads, canals, and eventually rails, while also using cheaper immigrant labor to build those things; using slaves to do these projects creates a less favorable balance sheet for the owner, because bodies that you own and are mandated to take responsibility for cannot simply be fired and replaced with new ones if they are too weak to work.
This tension of old vs new wealth also propelled western expansion, since it led to the "1 free state per slave state" dynamic to maintain political consensus, only for it to hit an abrupt ending in the 1850's when expansion reached the West Coast.