The real fear - and we'll address it in the next Federalist - is that were the country heavily regionalized instead of united there would be inevitable conflicts of interest that could be exploited by Europeans who would end up owning the middle by playing off the two sides against one another. They were very good at that, as the upcoming "Golden" Age of colonialism would prove to the dismay of everyone from Africa to Indonesia.
It was eventually the Monroe Doctrine that kept that from happening in North America (any more than it already had), which was planned by Monroe, John Quincy Adams...and the British. It seems counterintuitive but the Brits really did have some very effective strategic thinkers, and they ended up throttling the ability of their European rivals to conduct proxy wars on this continent, protecting both their Canadian and Caribbean claims.
One of the former almost brought the two sides to war shortly before the Civil War. I have to work the story of the Pig War into this because it cracks me up, and some of the names involved - George Pickett and Winfield Scott - would figure large in the big war to come on the other side of the continent. One participant reportedly said "Two great nations are going to war over what?"
Thanks!
I’m surprised that foreign influences did not win a heavier hand in the formation of the US, or in the war over secession. I appreciate the lesson!