It's homogenization, not gerrymandering
The New York Times reports: The buzz these days is that American politics may be entering a “postpartisan” era, as a new generation finds the old ideological quarrels among baby boomers to be increasingly irrelevant. In reality, matters are not so simple. Far from being postpartisan, today’s young adults are significantly more likely to identify as Democrats than were their predecessors. Along with colleagues at the Brookings and Hoover institutions, we recently completed a comprehensive study of the nation’s polarization. Our research concludes not only that the ideological differences between the political parties are growing but also that they have become embedded in American society itself. ...
But polarization has proceeded even further than these shifts made necessary. The great majority of voters now fuse their party identification, ideology and decisions in the voting booth. The share of Democrats who could be called conservative has shrunk, and so has the share of liberal Republicans. The American National Election Studies asks voters a series of issues-based questions and then arrays respondents along a 15-point scale from -7 (the most liberal) to +7 (the most conservative). These data indicate that 41 percent of the voters in 1984 were located at or near the midpoint of the ideological spectrum, compared with only 28 percent in 2004. Meanwhile, the percentage of voters clustering toward the left and right tails of the spectrum rose from 10 to 23 percent. ...
Our study shows that this geographical sorting worsens polarization in several ways. When counties become more homogeneous, it becomes harder to use redistricting to create more competitive Congressional districts. (Recent research indicates that gerrymandering accounts for, at the very most, one-third of noncompetitive districts in the House of Representatives.) When states become more homogeneous, presidential campaigns begin by conceding a large number of contests to the opposition, disheartening their supporters in those states and increasing the majority’s electoral advantage. Polarization feeds on itself. -- Vote Like Thy Neighbor