It would be very surprising if there was not a strong trend of more dense->more Democratic, but the Dakotas and a few other large Democratic districts may moderate the trend a bit. I believe the majority of the nation's land area is still represented by Republicans, though the Democrats might have taken that had they won WY-AL instead of losing it narrowly.
Actually, I would guess there would an even stronger trend (more dense = more Democratic) at the Presidential level by congressional district.
