Link-hopping, hope you don't mind. Started out from matociquala's journal hopped to someone who quoted your question about the blue in the upper great plains, so I came over here because I wanted to comment:

I had the same question when I saw that map last year, and I did some research on a few of those bright plue patches. Most of them show nothing there on maps of their respective states -- half the county is federally protected wild area, and the other half doesn't even show a town, let alone a largely democratic city. So who's voting, I wondered? National Park Rangers? And why isn't there even the slightest tinge of purple?

It turns out that every blue patch I looked at is a reservation. Native American tribes who are really, really pissed with Bush.