I turned 18 just a short while before the 1980 election. When I went to the poll on election day, the President of the United States was a Democrat. Both Senators from Tennessee were Democrats. My US Representative was a Democrat. The Governor was a Democrat. Both my state house and state senate representative were Democrats. The county commissioner from our district was a Democrat. The sheriff was a Democrat. There was not a single Republican elected official on any level representing me.
That was hardly a unique experience. Just 25 years ago, many states were solidly Democratic. Now they're turning red. My mother's home state of West Virginia is another prime example. She grew up in a coal mining family. Her dad and all four of her brothers spent a significant part of their lives underground (and paid the health consequences for it). They were loyal union men and the epitome of yellow dog Democrats.
The reason the Democrats are having so much trouble at the national level (and it's trickling down to the state level more and more) is not my uncles, even though a couple of them have switched too, but my cousins (and me of course). People who once would have been loyal Democratic voters for life now rarely if ever vote that way.
There are probably as many explanations for this trend as there are members of it, but I'd like to offer one in particular...Ronald Reagan. A couple of years ago, the kids took a government/civics class. We still had one of my old textbooks hanging around from the early 80s. This book, done by a conservative Christian textbook company was a huge eyeopener for my kids. It was filled with a defeatist and pessimistic worldview. My son said, "Reading this, it sounds like they thought the Communists were going to take over the world." I said, "They did. We did. We were losing the Cold War when I was growing up." That all changed with Reagan.
He gave voice to the beliefs about America that were shared across the political divide--after all he had been an FDR Democrat--and gave people hope and a vision for a freer world in which we would triumph over the "evil empire." He made it acceptable to vote Republican...and many of those who did never went back. It's taken some time for the full effects of that to permeate through the culture. But the culture shift is very real. (And by the way, the defeatist rhetoric of too many Democrats--and some Republicans too, cough Chuck Hagel cough--is not a winning strategy, either politically or in the real world. Part of the genius of Reagan was a belief that we could, should, and would win.)