What do Americans describe themselves in terms of ethnicity?

If you were born in the U.S. then you are considered American technically. However, most Americans will identify you by race. So if you are Puerto Rican, Spanish, Indian, etc, you are considered of "foreign" decent. If you were not born here, forget it, you are a foreigner. Even if you obtain citizenship, you are not American. Same goes in the opposite direction. If I move to Mexico, and live there for twenty years, I am still not a Mexican! I have blonde hair and blue eyes.