In Orange County, California, Democrats flipped the Presidential Result in 2016, and took the voter registration lead in 2019. This is a gap of 3 years. Its shocking how fast this took when comparing it to various situations in Appalachia.
There are many Counties in Appalachia where Democratic voter registration leads have held themselves for decades after the County started voting Republican at the Presidential level and never looked back in that front. Democrats still have voter registration leads in these places.
In West VirginiaThe following Counties last voted D for president in 1996, and currently have D voter registration leads:
Cabell, Calhoun, Clay, Gilmer, Greenbrier, Hancock, Hardy, Marshall, Mason, Mercer, Nicholas, Ohio, Pendleton, Pleasants, Pocahontas, Raleigh, Randolph, Summers, Taylor, Tucker, Wayne, Wetzel
The state of West Virginia currently lacks longer streaks where Democrats still have the lead.
But it gets even slower in Kentucky for things to switch.
In KentuckyHardin County as an example last voted Democratic in 1976 yet still has a D voter registration lead.
I am not going to go through and list all the crazy examples in Kentucky, because that would be extremely difficult, but there are at least 2 other example of Counties that last voted Democratic in 1980 that still have D voter registration leads too.
I am not going to even bother checking Tennessee or Virginia right now, but there are probably some in those states too.
Maybe I could even find a few elsewhere as well, though I doubt it.