Really? I was born and grew up in a suburb of Chicago, but have since then lived in Los Angeles, Houston, Atlanta, and a few other places, and have rarely felt that my born-in-Chicagoness was at all an important or a distinguishing factor. There are Americans I don't have a lot in common with, but it doesn't have much to do with where we were born. For example, I don't tend to get along with people who have anti-intellectual views, but you find those (and their opposite) anywhere. I think of myself as "American", but I would be hard-pressed to think of anything particularly "Chicagoan" about me. It'd be something trivial like hot-dog or pizza preference, probably.

As far as geography goes, I see more differences within than between regions. I don't have a lot in common with people who live in very rural areas, for example. But e.g. a coffee shop in Midtown Atlanta doesn't feel that much different from a coffee shop in Brooklyn or Westwood. And the Atlanta suburbs don't feel that different from the Chicago suburbs.

What? Not even speaking English?

Someone born and raised in New York City probably doesn't have that much in common with someone from upstate New York either.