Republicans lost in every region and were defeated in critical races even in the reddest of states, such as Kansas, Indiana and Arkansas. The Republicans are rapidly collapsing into a regional party -- the Party of the South -- and even there, they lost incumbents and vast amounts of their support. They have pandered to such a small and deranged band of extremists for so long, and they are now finally paying the price in the form of a disintegrating movement and continuously shrinking band of followers.
And here's Fred Barnes (via War & Piece):
The defeat for Republicans was short of devastating--but only a little short. The House seats the party lost in New York and Connecticut and Pennsylvania will be hard to win back. Just as Republicans have locked in their gains in the South over the past two decades, Democrats should be able to solidify their hold on seats in the Northeast, as the nation continues to split sharply along North-South lines.
What should worry Republicans most, however, is erosion of its strength in the West and in two states in particular: Colorado and Arizona. Fours years ago, Colorado was solidly Republican. Since then, Democrats have won a Senate seat, two House seats, the governorship, and both houses of the state legislature. At the state level, that's realignment.
So the Republicans suffered mightily in the Northeast, suffered somewhat in the West, and Democrats were able to contend in some traditional Southern strongholds. Is that realignment, or merely the GOP having a very bad mid-term? I don't know, but it's an interesting theory, and a nice counter to the oft-repeated (and inaccurate) meme that Democrats have become the party of the NE and the Coasts.