It may well be the "libertarian" factor that caused these counties to shift. Has anyone also thought about the collapse of the Nader vote? Nader got about 6% in Montana in 2000, but only 1% in 2004. Kerry's 39% is almost exactly that much pickup from Gore's 33%. Idaho has shifts that I think look similar.
If this is evidence of a Democratic swing, it's happening too slowly to make a difference, at least as far as Wyoming, Idaho, the Dakotas and Montana are concerned. Bush did better in Montana both times than Nixon did in 1972. Ditto Idaho. There may be geographical shifts in which counties vote more Democrat, but it doesn't seem to be tilting the overall vote.
Welcome!
Very nice first post.