While most Southern whites are primarily of English descent, I've heard that the more educated ones specifically identify as "English" while less educated ones identify "American".
For instance, Williamson County, TN is by far the most college-educated county in the state and also the only one where a plurality of residents specifically identify as English as opposed to American. Is there something distinct about the ancestry of people living in that particular county? I don't think so.
It's just one data point, but it's something to consider.
The correlation with Episcopalians is true in smaller towns in the South, but in the Northern cities that isn't the case, as Episcopalian congregations are increasingly made up of converts from other denominations (Catholic, Evangelical, etc.)
