Ongoing Polarization of the House in 1 Chart

In a 7-1 vote last week, a committee in Tennessee's state Legislature passed a bill to eliminate party primaries, an idea that strikes National Journal's Charlie Cook as really, really bad.

But the vote also lends credence to Cook's assertion, using his Partisan Vote Index to map House elections over 14 years, that polarization is increasing. That's because legislatures are doing whatever they can to keep congressional districts in friendly hands.

Cook polarization of the House chart
Cook polarization of the House chart

Source: Cook’s Tour of American Politics and Economics.
National Journal members can access the full deck at the Presentation Center or download it here.

Despite the decreasing number of possible swing elections, various contests continue to be pursued with vigor, including Tuesday’s Republican primary runoff in "ruby-red" South Carolina, where Democrats spy opportunity amid shifting demographics and political misfortune.