[QUOTE=saoirse]
your example also happens, as you say, in Illinois. Also Ohio and Indiana. And, as any football fan in this area can attest, Western Pennsylvania. I’ve heard it in Oklahoma, West Texas, and from people who grew up in Arizona and Colorado.
[/QUOTE]
You may recall that Oklahoma is where the Southern Indian tribes were re-settled. (More evidence that the Southern accent was in place by the 1830s when the removals occurred.)
West Texas, presumably, was peopled by east Texans. I regard it as part of the South.
As I mentioned before, many settlers in southern Illinois and southern Indiana came from the South. Abe Lincoln’s family migration from Kentucky is typical.
In both Southern Ohio and western Pennsylvania you have some bleed-over from the Appalachians (Kentucky and West Virginia).
I’ve never heard it in Colorado or Arizona, but it wouldn’t surprise me to hear it there, since parts of those states were also peopled (in large part) by Southerners moving west after the Civil War. (New Mexico, too.)
For that matter, you can also hear it in Bakersfield, California, where many of the “Okies” wound up.
None of that changes or challenges my essential point, which is that there is a fundamental divergence (in broad terms) between “Southern” accents and Northern accents. When you hear a Southern accent, you can recognize it as such, even if you can’t pinpoint precisely where the speaker is from?
(Note that even with your exceptions we are still talking about a geographically contiguous area, though its borders may not be strictly confined to the old Confederacy. You don’t hear the Southern “long i” in New York or Minnesota do you?)
If we recognize that the Southern accents diverge from the Northern ones, we have to ask when, how and why that divergence occured. Until I hear a better theory, the isolation of the Jamestown colony from the northern colonies makes sense to me as a starting point.