The US states were all founded by people who were generally of the same culture heritage, spoke the same language, had the same religious tradition (mostly British). In that sense, it began with a meta-culture based on shared values. It's all there in our founding docs. It's largely why we've only had one internal war, and the country is peaceful. It isn't true that that US govt manages the states. Each state manages its own affairs to varrying degrees of success. And even though there are 50 different states you can go to LA, Atlanta, Chicago and Dallas and have a fairly homogeneous experience. Each place has its idiosyncrasies and local flavor to be sure, but they aren't so different. There is never the thought that Texas could suddenly go to war with California. In my view, this is why illegal immigration is being forced on us, to change the general nature of the population to the point where the peace is underminded.