I don't necessarily mean the states -> USA relationship. One of the things I've come to understand, as a regular visitor to the US, is that there's a community for everybody. No matter how idiosyncratic (or even extreme) your political, social and economic preferences, you can find a community to take you in. And if you can't, you can create one and find others of like mind. And somehow it all still comes under a single umbrella notion of being "American". This exists practically nowhere else on earth. And I say that as a resident & citizen of another country that has a federated state structure.

And yes, I know it's a work in progress, and that this hasn't lead to equity of representation or systemic fairness. But still, in my view, establishing that framework and unifying je ne sais quoi in the face of such diversity is the single greatest political accomplishment of the last few hundred years.