randomslasher answered:
Because there are massive regional differences in the United States. It may be nuance that’s lost on folks outside the country–I can’t speak to that–but someone from California is going to be assumed to be a lot more liberal (and therefore against the current administration and its bigoted actions) than someone from, say, Kansas (a midwestern state that always goes red in election years). There are lots of reasons different parts of the country identify in different ways–agricultural, economic, and geographic reasons that certain ideologies find a home in certain physical locations–but I won’t go into that here.
The point is, identifying as “American” feels very different, at least to Americans, than identifying as, say, a New Yorker, or a Californian. Identifying as part of a region known for liberalism BEFORE identifying as “American” is a way of putting distance between yourself and the bad parts of the United States.
Additionally, the rampant nationalism of the US makes some of us uncomfortable with acts of patriotism of any kind. I can’t even say “I’m American” without feeling like I need a shower afterward, because the whole “Proud to be an American!” culture is the poster front of the groups now heading white supremist, fascist, and bigoted agendas that I and many other people in my country want nothing to do with.
When your country has gotten so bad that even claiming to be from there gives you a sense of deep-seated shame, you do whatever you can to alleviate that shame. Is it right? Maybe, maybe not–perhaps we SHOULD be claiming to be American while pushing our own agendas (peace, acceptance, tolerance, humanitarianism, etc.) so that the association of the word will change. I don’t know. That’s a bigger question than I can easily answer from my layman’s armchair. Like I made clear in my post, I don’t know for sure if that’s where the tendency to identify as a region or state-specific American or to claim the heritage of one’s ancestors comes from.
It just seems reasonably likely, given the state of things.