Kansas, however, is consistent: solidly Republican then, solidly Republican now.
It's easy to understand why the once-solidly DemonRAT South became Republican. The old FDR-style leftists of the region died off and the "New South" with a pro-business, anti-union Right-to-Work mindset emerged. That paved the way for the remarkable Conservative triumph across Dixie.
What's harder to explain is why Yankeeland took a turn to the DemonRAT party and its leftism. In particular, New England was once staunchly Conservative, going back to John Quincy Adams, Charles Sumner and, of course, President Calvin Coolidge. He'd be appalled at his home state of Vermont not only supported the obama cabal by staggering numbers but has an out-and-out socialist serving in the Senate, Bernie Sanders.
The leftist book, What's the Matter with Kansas? is totally wrong for there are very few things wrong with the Sunflower State. Instead, a more apt title would be What's the Matter with New England? due to its repudiation of its Conservatism heritage, replacing it with extreme liberalism.