I posted recently about some reading I've done, including Orson Scott Card's Empire. Imagine my surprise when I read this article this morning.
Basically, the main idea of the article is this: each time a democrat becomes president after eight years of a republican president, some far-right people go crazy and start committing terrorist acts.
Interestingly enough, when the change is from democrat to republican, far-left people don't commit acts of terror.
Interesting correlation and some good evidence for what I thought was common sense: republicans fight with guns, democrats fight with words (but Orson Scott Card obviously disagrees).