Republicans won a huge victory in the House, and -- as Nate Silver explained at 4:15 AM, a time stamp that makes me only slightly skeptical of his conclusion -- they won more seats than you'd expect given their share of the overall vote. This is the third straight "wave" election in the House, and one might think the pattern could recur for a while, with control shifting back and forth. I doubt it. Get used to Republican control of the House of Representatives. It's going to stay that way for a long time.
Why are Republicans in strong position to hold the House? Three reasons:
1. Natural geography. Even if House districts were drawn up with no partisan tilt in mind, Republicans would have a natural advantage. Democrats are frequently clustered together in overwhelmingly Democratic districts, creating ultra-safe seats that waste votes. There are fewer districts that are equally concentrated with Republican voters.
Thus Republicans can win the House even if they don't have more voters who support them. The median House district is about 3 percentage points more Republican than the nation as a whole. In order to hold the House, Democrats need to control a lot of Republican areas, some of them extremely Republican areas. The GOP is much less dependent on holding onto seats in unfriendly territory.
2. Redistricting. If that's not a problem enough for Democrats, it's about to get a lot worse. Republicans had their wave election at a very convenient time, putting themselves in position to control numerous state legislatures and thus control the next round of redistricting, which will last a decade. Partisan gerrymandering can be an extremely powerful tool, and combined with the natural geographic gerrymander, can give Republicans an overwhelming advantage, if not quite an absolute lock.
3. Timing. The best way to have a wave election is to have the other party control the presidency during a bad economy or some kind of major scandal. Democratic waves in 2006 or 2008 owed a great deal to the non-existent income growth during the Bush years. The GOP wave owed a great deal to the economic crisis. But in 2012, Democrats will still have the White House, so they won't benefit from an anti-incumbent wave. (They may pick up some seats due to sporadic voters re-engaging.) The best hope of a big wave would come from a deep and extended economic crisis that gives Republicans control of government in 2012, continues through 2014 and paves the way for a midterm backlash. But that's not exactly a positive scenario.
As long as Republicans control the House, the prospects for progressive or even good-government technocratic legislation (to reduce the deficit or reform the tax code, say) are probably nil. So enjoy the legislative triumphs of Obama's first two years, because that's going to be it for a while.