Self-identified "Americans," on the Census, correspond largely to White Southerners, who in turn are primarily a mixture, culturally speaking, of Southern English aristocrats and their indentured servants and Northern English/Scots-Irish yeomen.
In a more general sense, "Americans" are split along various regional faultlines. In colonial times, the main four corresponded loosely to New England, the Middle Colonies, the South, and the Appalachian Backcountry, with origins in the Southern English bourgeoisie, the Midlanders, the Southern English aristocracy, and the Northern English/Scots-Irish respectively. The West Coast and coastal Great Lakes emerged largely as a result of New England expansion, the interior West and the non-coastal Great Lakes as a result of Middle Colonies expansion.
Oftentimes American regions have had more in common with adjacent Canadian provinces than with other Americans, like Portland feeling more at home with Vancouver than with Birmingham, or Boston being more like Halifax than like Tucson.
Ultimately, there are some four root Anglo-American cultures and two additional cultures derived from those, if we want to simplify to the greatest degree. Each sees itself as the truest form of America and the others as heresy.
