The die for sectional tensions was cast pretty early on. The South was a de facto British colony, arguably, until the Civil War (almost all Southern cotton was destined for British mills). The rapidly industrializing North represented a radically different future for the country, and the political conflict between North and South over economic and trade policy took shape very early on, particularly over tariffs. To people in the North, it made sense to protect burgeoning domestic industries from foreign (British) competition. Southerners, on the other hand, had no interest in manufactures and generally saw tariffs as taxes falling disproportionately on them, as they preferred cheap goods from Europe (Britain).
Alexis de Tocqueville famously noted the differences in industrial development between slave and free states. But Southerners (at least those with slaves) generally defended slavery as an institution and equated the plantation system with the "Southern way of life". And, by all accounts, even if they hadn't, white supremacism was so deep and broad it's unlikely any kind of economic concerns would have been able to overcome it in any policy debate.
You skip over the part where a weak central government utterly failed to meet the most basic expectations of the citizens of the new republic.
Also, I think Keynes should win a posthumous award solely on the basis of your comment. It's quite a feat to retroactively influence the policy of a government across a chasm of almost two centuries.
Alexis de Tocqueville famously noted the differences in industrial development between slave and free states. But Southerners (at least those with slaves) generally defended slavery as an institution and equated the plantation system with the "Southern way of life". And, by all accounts, even if they hadn't, white supremacism was so deep and broad it's unlikely any kind of economic concerns would have been able to overcome it in any policy debate.