I agree, this is a really, really cool visualization of something that would otherwise be rather difficult to understand. I've always known about the "Southern switch" but something like this really highlights it. Alabama in particular had a almost 83% change in the vote from 1960 to 1964 and a 73% swing back in 1968! It's also cool to see the slowly cyclical nature of the elections, although the wild swings from one party to another seem to have slowed down quite a bit.