From the National Center for Policy Analysis, an overview of a report stating that 10-15% of polarization is due to gerrymandering. This is lower than previous claims. They conclude that each party is simply more in tune with the preferences of those who identify with them:
When Massachusetts Governor Elbridge Gerry signed off on a particularly distorted legislative district in 1812, bequeathing the "gerrymander" to American politics, did he lay the groundwork for today's partisan rancor? That's the question three political science professors set out to answer. Ever-more-sophisticated gerrymandering techniques protect the jobs of incumbent politicians, the usual theory goes, allowing them to ignore moderates and indulge the whims of their most bloodthirsty constituents.
Clearly, a seat on Capitol Hill is one of the safest jobs around:
o In 2002 and 2004, for instance, 99 percent of competing incumbents in the House held on to their jobs.
o Even the Democratic surge in the last election didn't prevent 89 percent of House Republicans from keeping their seats.
o Yet the professors argue that gerrymandering bears little responsibility for the collapse of bipartisanship.
Their analysis of recent congressional voting records shows that polarization has increased nearly as much in the gerrymander-proof Senate as in the House. One of the best explanations for a Congress where most politicians vote a straight party line is simply that political parties are now better aligned with the views of their constituents than they were 50 years ago. Republicans, for instance, have won the loyalty of conservative southerners who used to
vote Democratic, and Democrats increasingly represent northeastern moderates who used to support the GOP.
The effect of gerrymandering on this kind of "sorting" was approximately zero, the authors found. Overall, they conclude that gerrymandering accounts for, at most, 10 to 15 percent of the upswing in polarization since the 1970s.
Source: "Safe Seats, Crazy Partisans?" The Atlantic, March
2008; based upon: Nolan McCarty, Keith T. Poole and Howard Rosenthal,
"Does Gerrymandering Cause Polarization," Princeton
University/University of California at San Diego/New York University,
October 23, 2006.
For text:
http://www.theatlantic.com/doc/200803/primarysources
For study:
http://www.princeton.edu/~nmccarty/gerrymander11.pdf
