Times were so tough in the coal mining region around Buchanan County, Va., in 2016 that people looked for a political savior. They got Donald Trump. A year after his inauguration, they say it is working out just fine.

Gary Palmer had been laid off from local mines three times. In 2015 he moved four hours away to take a construction job in West Virginia and saw his wife and four children just once a month. After Mr. Trump’s election, with mines reopening, he moved back. “If the election had gone the other way, I don’t think...