Mississippi is strange on that map.
Most people don't know that, but Mississippi has supermajority white parts and these parts had a considerable, if minority, Democratic vote up until 2004. Those are
hard swings in the corners.
Oh, and Black turnout was lower than White for a very long time - contrast Louisiana where that wasn't the case.
If Dems had somehow managed to get the Black turnout up without alienating their hillbilly voters (both in the quasi-Appalachian Northeast corner and in the Piney Belt - an area just north of the coastal counties (continuing into Alabama) that was largely uninhabited between Indian Removal and the latter 19th century, btw - you'd be looking at a genuine swing state now.
P.S: Any prospect of a 1988-2012 swing map?
That would definitely take a new color scheme. Given how hard some of those dark shades in the Atlas Standard Key are to differentiate anyways, I didn't go past +30 (American terminology, so really +15)... but some of those Appalachian swings are much higher, a few over twice that. There's counties that Gore and Romney both got about 2/3 of the vote in. With 1988 to 2012, even more of the map'd be a sea of dark colors without a new color scheme.