Ha, well, as Chris points out....except for the parts of the US that aren't homogeneous, the US is homogeneous! You don't say!
But, I am wondering about the parts of the US that Chris dismisses as exceptions. I am not Amish but I live in the heart of it, and the local culture is one part "Pennsylvania Dutch", one part Puerto Rican, and one part Vietnamese - or so it looks during our city festivals. The people of Wasilla, Alaska are much more foreign to me than people from Puerto Rico.
We could also compare the town of Paia Bay on the island of Maui, and the town of Charleston, Mississippi, which up until 2008 held racially segregated high school proms.
All of these places share the "US culture", yet they are all distinct.
Matt
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