Does it means whites of English ancestry or does it mean elite whites of English ancestry that belong to mainline churches but not fundamentalists?
If we use the former definition, Kentucky, say, would be a lot more "WASP" than Connecticut, but if we use the latter Connecticut would be more "WASP."
It's also interesting how census responses have a regional and class basis to them. In New England and among the affluent, people are more inclined to declare English ancestry while in the South, they're more likely to say "American."
Scotch-Irish identity seems to be a Southern working class and rural phenomenon. Though I should add the so-called "Celtic thesis" is garbage.
Whites with roots in New England are more likely to be of English ancestry than whites with roots in the South and Appalachia, whose ancestors more likely came from the southern part of Scotland or from what is now Northern Ireland.
Actually there's also-in addition to the Scottish and Irish Protestant ancestries-a lot of English, Welsh, French Huguenot, and German Palatine in the "Scots-Irish" mix of cultural groups. And that's not even taking into account all of the French, German, Dutch, Czech, etc. that have all contributed to the South's ancestral makeup. And what of the Native American and black ancestry that many Southern whites likely have?
The issue here, like the OP said, is that Southern whites were (and still are, to some extent) poorer and less educated than Northern whites, generally speaking. Thus, many
truly don't know where their ancestors came from; a lot of those ancestors are lost to history. Also, the South didn't receive much immigration from Europe after 1800.
All of these are among the factors (besides excessive nationalistic pride
) for the common Southern/Appalachian, etc. phenomenon of whites putting "American" on the Census.