The electoral boundaries set based on who was in office in 2010 have a way of sticking around in most areas. I note that in 2012, Democrats won the sum total of House votes 48.8% to 48.5%, while the Republicans retain the House by a significant margin, 232-200 actual Congressmen. The Republicans invested heavily in winning state legislatures before this period, and are now reaping the rewards in gerrymandered districts.