One reason for the shape of things is the distribution of the population. Democrats are now packed more closely in urban areas. Republicans are more evenly distributed across suburbs, exurbs and rural areas. That means Democratic House candidates win by large margins, but many of those votes are in essence wasted. For many years now, more congressional districts favored Republicans than Democrats. But that advantage is more important today because loyalty to party has a greater influence on how people vote.
The bunching of Democrats in urban areas is clearer from a look at county-by-county results from last year’s presidential election. Obama won just 705 of the nation’s 3,153 counties. But Rhodes Cook, an independent analyst of political trends, points out that the president won “the bulk of those counties that really mattered.”
Congressional results from 2012.
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Obama won 35 of the 39 counties with populations of 1 million people or more. He won those counties by a margin of 8 million votes. He lost the rest of the country by about 3 million.
An unprecedented gulf
Ideological polarization in the House is wider than it has ever been. The last time it approached today’s levels was after the Civil War, in the late 19th century. Nolan McCarty, a political science professor at Princeton University, has helped chart those changes, along with the scholars who first created the index, Keith Poole of the University of Georgia and Howard Rosenthal of New York University.
Calling the period during Reconstruction “a highly polarized time,” McCarty said: “Our measures today are far worse than we observed then. We’re almost at the point where we can’t measure further increases.”
Today, there is almost no overlap between the voting behavior of the most conservative Democrats in the House and the most liberal Republicans. That’s in part because there are few moderate-to-conservative Democrats and moderate-to-liberal Republicans left in the chamber.
It also is a reflection of the fact that members from districts that are more evenly balanced ideologically now vote the way their colleagues from highly ideological districts vote. In other words, there is a big difference in the way Republicans and Democrats represent relatively neutral districts.
“Even in districts that turn over a lot, the gap between Republicans and Democrats in those districts has grown tremendously,” McCarty said.
Much of this has resulted from well-documented changes that have made each party more homogenous than in earlier eras. Two shifts account for many of these changes. The first is the realignment of the South, which has become solidly Republican. The second is the realignment outside the South with the decline of the liberal wing of the Republican Party in the Northeast and Midwest.
The parties also are more divided racially than before. The Republican Party is almost entirely dependent on white voters. Nine of every 10 votes Romney received were from white voters, according to exit polls. Democrats are increasingly dependent on support from nonwhite voters. Obama got 44 percent of his votes from nonwhite voters.