Nate Silver has a fascinating post on this question. Here’s his answer:
Individual members of Congress are responding fairly rationally to their incentives. Most members of the House now come from hyperpartisan districts where they face essentially no threat of losing their seat to the other party. Instead, primary challenges, especially for Republicans, may be the more serious risk.
Here’s a figure which shows the number of swing districts, whose vote share for the Democratic candidate for president was close to his national vote share, shrinking overtime.
Silver continues with some interesting data on increasing polarization and reduced split-ticket voting, then concludes with a less than inspiring prediction about the likelihood of seeing a less dysfunctional House.
They remain in control of the House of Representatives, in part because the median Congressional district is now about five points Republican-leaning relative to the country as a whole. Why this asymmetry? It’s partly because Republicans created boundaries efficiently in redistricting and partly because the most Democratic districts in the country, like those in urban portions of New York or Chicago, are even more Democratic than the reddest districts of the country are Republican, meaning there are fewer Democratic voters remaining to distribute to swing districts.
[...] because of the way districts are configured, their position in the Houseshould be quite robust: it would require a Democratic wave year, and not a merely decent election for Democrats, as in 2012, for Republicans to lose control of the House.
These strengths and weaknesses for the Republican Party could be self-reinforcing, or at least they may have the same root cause. The district boundaries that give Republicans such strength in the House may also impede the party’s ability to compromise, reducing their ability to appeal to the broader-based coalitions of voters so as to maximize their chances of winning Senate and presidential races. If so, however, that could mean divided government more often than not in the years ahead, with Republicans usually controlling the House while Democrats usually hold the Senate, the presidency, or both. As partisanship continues to increase, a divided government may increasingly mean a dysfunctional one.
HT Daniel Gross