Matthew Yglesias discusses how West Virginia used to be a Democratic state but is now solidly Republican. I thought it would be helpful to expand this to look at trends since 1948 (rather than just 1988) and all 50 states (rather than just one). This would represent a bit of work, except that I already did it a couple years ago, so here it is (right-click on the image to see the whole thing):
I cheated a bit to get reasonable-looking groupings, for example putting Indiana in the Border South rather than Midwest, and putting Alaska in Mountain West and Hawaii in West Coast. Also, it would help to distinguish states by color (to be able to disentangle New Jersey and Delaware, for example) but we didn’t do this because the book is mostly black and white.
In any case, the picture makes it clear that there have been strong regional trends all over during the past sixty years.
P.S. My graph comes from Red State Blue State so no 2008 data, but 2008 was pretty much a shift of 2004 so you’re not missing much except for an exciting downward spike for Hawaii.
P.P.S. I’m not sure where Yglesias got his data. He shows West Virginia as +15 for the Democrats compared to the national average in 1992. But when I looked it up, Clinton got 48.4% in WV compared to 43.0% nationally. That looks like +5.4, not +15. I’m guessing that this was just a typo somewhere. In any case, I’m always happy to have an excuse to repost graphs from Red State Blue State, and to demonstrate the advantages of the small-multiples plot.