This conception of nations (plural) isn't that far-fetched. "Albion's Seed" makes a great anthropological study of four different colonial cultures (Puritans, Cavaliers, Quakers, Scotch-Irish) that give rise to enduring regional difference even in modern-day America.
Funny enough, I'm currently reading "American Gods" by Neil Gaiman, wherein the main characters contend that while there may be geographical proximity (on the continental scale), the variegated parts of the U.S. are actually different countries:
"San Francisco isn’t in the same country as Lakeside anymore than New Orleans is in the same country as New York, or Miami is in the same country as Minneapolis."
"Is that so?" said Shadow, mildly.
"Indeed it is. They may share certain cultural signifiers—money, a federal government, entertainment—it’s the same land, obviously—but the only things that give it the illusion of being one country are the greenback, The Tonight Show, and McDonald’s."