While I agree with his general thrust–that (as Iraq seems to many) the early US didn’t look for very promising for forming a government either–Publius errs slightly when he writes:
There were Scottish, Irish, English, Indians, Dutch, French, Germans, and those who had lived in America since its founding. And more; many speaking languages other than English at the time.
Yet we ended up with a Constitution and a country to rally around. Our eventual Civil War was never fought on the basis of ethnic differences either, but serious compounding issues over nearly forty years that led to a war not of national origin, but of the preservation of our nation.
The roots of the War Between the States did in fact lie (at least partly) in national (or at least regional) origin. It was a war between groups of people descended from the English settlers who first settled North America. The Union was an alliance of the Puritans of New England (originally from East Anglia) and the Quakers of the Delaware Valley (originally from the Midlands), fighting against the Confederacy, which was an alliance of the Cavaliers of southwest England who settled the Tidewater country of Virginia and the Piedmont and the redneck Presbyterians from the borderlands and Ulster who had colonized Appalachia and the deep south. The war was to a large degree a fight over different conceptions of liberty, and in some senses, could be said to be an echo of the English Civil War, with a similar result.
For more information, read Albion’s Seed, by David Hackett Fischer.