I saw it but intended to comment on it anyways.
This is very interesting, btw. I didn't know that. Much of West Tennessee was in Union hands for most of the war, of course, and I *did* know about the Union sympathies of much of Northwest Alabama. (Oh, and more than a third of Tennessee's Civil War vets fought for the North. That is a higher than WVa's proportion of Civil War vets that fought for the South - even without any attempt to purge the lists of people who enlisted for Virginia or Tennessee before it was even clear what side they'd be on and went home as soon as they could (and those numbers are fairly high).
Also, why did the heavily pro-Union, Republican tradition in eastern Tennessee never spill over into western North Carolina?
It did. Northwestern North Carolina, to be precise. Transportation links played a major role in determining mountain areas' allegiance during the war - areas with good links to the east coast were pro secession even when not dependent on slavery - see also southwest Virginia. Areas with good links to the Northwest interior (what you'd call the Midwest now), not.
