Very interesting... And quite troubling.

But, do you really believe THEY ARE NOT ENOUGH? I mean, the principles, the ideas, ideals and insights that keep the USA glued together...?

I have not lived there long, so I cannot tell for sure, but... What is seen from abroad, is such a coherent block of Unity and Will! "The will of the people is the will of the people"...!

On the other hand, I'd say you may be wrong about the USA not being founded on historical or cultural (or geographical) reasons; the original Thirteen Colonies, even before the spark of Independence was lit, had in common a single heritage of European descent, of Irish-German-English blood, and in truth, they were more of a "branch" of European races and cultures...

But then again, the ancestry of Rome, the Vikings and the Celts COMBINED may be too war-stained to be reliable... So maybe that is in fact what keeps pushing them apart... Europeans have always waged the most epic ("sad") wars in history, lets not forget that...

Also, the strip of land from Boston and New England to Georgia (Florida was taken from the Spanish, as we all know) was quite coherent geographically; the obvious next-step was to expand west and southwards, into the lands of the Mexican Empire (their Austrian Emperor too far away to do anything about it)... And so they did, and so they did... Taking for themselves the borders with Canada onto the State of Oregon, and everything that led them into and beyond Texas, including Nevada and California...

So if you look at it from the perspective of most human expansions in history, it does make a lot of sense, and it does add to the American "National" feeling, just as it happened to the Roman and Persian Empires, Ancient China, Russia under the Tzars, Napoleonic France... And a long, long et cetera...