re: Why was coal country still democratic well into the 1990s and early 2000s?

I think people are being a little simplistic about this. I've spent a lot of time in Appalachia and specifically WV.

Yes mining unions and the terrible history of labor relations in that state were a major reason why it continued to vote democrat. But another reason is that WV is one of the biggest "winners" when it comes to federal funding. As a state with really tough terrain and almost no money, WV has always been very reliant on the Feds to provide for infrastructure, jobs and services. For a long time Robert C Byrd was able to deliver huge infrastructure projects that not only improved the state but provided jobs. Seriously, drive around the state and see how many bridges and highways are named after him.

Democratic Presidents have spent the last 80 years going into WV and Eastern Kentucky to launch New Deals and Wars on Poverty. The populace believed it and some of them did actually benefit. Political inertia took over from there.

They continued to vote for the Dems long after it was in their self interest, but I was in WV in 2008-09. The switch when Obama won was almost instant. It also coincided with the death of Byrd. Life long Dems when flying to the right.