There is a distinct area which many characterize as ‘Appalachia’ that emerges distinctly when you look at the counties that voted for McCain in 2008 by a higher margin than for Bush in 2004. The strong temptation is to write this off as ‘racism’, but I don’t think that’s technically accurate.
What must be remembered is the regional divide between what in Virginia were known as the ‘tuckahoe’ and ‘cohee’ - between the early Baptist Scots-Irish subsistence pastoralists and later primary truck-workers and the largely Anglican planter aristocracy which wound up decaying and then modernizing into what we know as the Deep South.

These areas were electrified and linked firmly to the outside world in living memory; except for the areas overlapping with the Rust Belt they’ve never had a major stake in American exports or the global economy, and - most importantly - they were never host to any serious attempts at slave-holding plantations, were subject to only extremely sporadic and occasional black migration from the Deep South, and have never seen significant immigration and only very rarely have even seen internal emigration (the large exception being the initial wave of Scots-Irish settlers moving inward as usable tidewater land became valuable for cotton production and the pre-Revolutionary strictures on westward movement disappeared - and those largely settled the westward leg of the Cohee boomerang).
As Tim Krieder suggested in The Pain - When Will It End’s America’s Scum Belt, the motto of the area could well be ‘You ain’t from around here, are you?’ - not exactly hostile, but far from friendly, and a gentle and constant reminder of the area’s fundamental resistance to outside influence. The post-Civil War mainstreaming of pro-Confederate opinion in the area spawned the secondary, ahistoric rallying cry of the secessionist and states’ rights movement - ‘We just want to be left alone’.
Clinton’s campaign, which faced after Super Tuesday a primary map which was nothing like as favorable as she would have needed to cinch the nomination before the convention, realized that there was one reliable way to get the whites of the South, who had (with few exceptions) gained little from racism and didn’t hold the oppression of blacks as near and dear as the Republicans had hoped - pointing out Obama’s exoticness.
Not in general terms, either - he was an elitist! a bold young man, in stark contrast with the region’s tradition of political lifers! Maybe possibly just could be gay, certainly not a member of their church, and by God, a black- just like they have in Richmond!
This was a sound strategy for capturing the region, but the problem is that even coming from a campaign with reasonable liberal bonafides, the entire exercise stank to outside observers of racism. Clinton won Pennsylvania but lost the Carolinas, which should have been clear evidence that she wasn’t going to smash Obama in the border South so badly that the convention would decide anything.
Of course, there’s nothing the Republicans like more than other people’s ideas, and sure enough the McCain campaign decided to plagarize this one. They started drawing contrasts between the Democrats and ‘real Americans’, started calling the tidelanders Communists, started suggesting that Obama wasn’t just black but a dangerous radical.
This didn’t exactly endear him to the High Cohee - after all, they don’t believe they have a monopoly on being Americans, they were (witness Pogo, for Chrissake) pretty indifferent to red-baiting throughout modern history, and they had less objection to blackness per se than its presence in their lives.
But the fallout was incredible. In a moment, the flailing effort to capture the south of Virginia suddenly alienated everyone outside of its panhandle - he was clearly trying to pander to a group that everyone outside of Appalachia saw as ignorant hicks, and he wasn’t even doing it convincingly. You can excuse Clinton’s seeming race-baiting away on it simply being how things work in Appalachia, but a campaign comprising an Arizonan and an Alaskan couldn’t come even close to pretending that. It won him West Virginia, but it cracked the Republican hold on the Deep South - which knew and held in contempt the cohee opinion of their big-city decadence - and it’s probably opened a suppurating wound in the Southern Strategy.
In short: we can excuse away charges of ‘racism’ against the Clinton campaign on this basis. They knew the difference, in a way it would take someone from Appalachia to be familiar with, between hating blacks and holding everything outside the near and familiar world in a sort of sweeping contempt - but that difference never occurred to anyone on McCain’s staff. Huckabee might have been able to pull it off - but McCain’s dog whistle was never even close to inaudible. Heck of a job, Johnny.