Do you mean that there's no difference between organizing at the state and federal levels, given the cultural variety at each of those levels?

Maybe that means we should go smaller? Swiss cantons average 330k people each (8.5 million population, 26 cantons), and each canton has responsibility for their own healthcare, welfare, law enforcement, public education, tax policy, its own constitution, and can enter into treaties with other cantons and even foreign countries. Their federal government is very limited. The seem to do a pretty good job. When they have a minority problem they can't fix, they split them off a new canton.

In my prior comment I had been thinking of the balance of powers between the states and the federal government. I think the tenth amendment is important, that the division of powers between the states and the federal government is just as fundamentally important as the balance of powers between the three branches within the federal government. As the federal government grows larger it grows more corrupt, dysfunctional, and disconnected from the people, as all unchecked powers tend to do.

Speaking of shared culture, and this balance of power, things have devolved to the point where we argue every four years over the entire direction of the country personified in one person, the president, tribal leader and hopeful superman to 51% of the population, and cause of all that is wrong for the other 49%. We get our facts from the news, often nothing to do with our real lives and experiences. Details are nuances are ignored, there are too many anyways. The president is the team leader. Other people are stupid and liars and evil and all that matters is that your team wins. This is not going in a good direction! This isn't a problem with the voters, it's a problem with the system.

My two cents :-)