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Welcome to a more politically polarized US

Over the past decades, the US has become more polarized politically, with more representatives voting along party lines, ideology more aligned with party, party more aligned with certain demographic groups, and more geographic differentiation.

Gregory F Treverton writes,

“Looking at the data provides support for what many observers note: the country has become more polarized. One study examined all roll call votes in the House and Senate, then plotted the average difference between Republicans and Democrats. In 1973 the difference was .55 but had grown to .95 by 2003. Of that difference, Republicans contributed .3 and Democrats .1, providing some support for the proposition that Republicans have become even more ideological than Democrats.8 Since the early 1970s ideological preference has become more closely aligned with party identification.

Over the last half century, party identification has become more demographically distinct. African-Americans more solidly identified as Democrats; Southern whites and churchgoers more aligned with Republicans; college educated moving towards Democrats.

How to explain the growth of polarization? By one popular argument, it is not primarily gerrymandering that produces safe districts. Rather, Americans have more and more sorted themselves into geographic communities of like-minded.10 For instance, people with college degrees were relatively evenly spread across the nation's cities in 1970. Thirty years later, college graduates had congregated in particular cities. Using limited demographic information to determine a given congressional district‟s voting pattern was twice as successful for 2003 as for 1973. By this argument, the echo-chambers are plural, and they are physical as well as virtual. People find the sources that reinforce the opinions they already hold. Drawing congressional districts in some random fashion would not reduce polarization because it would still produce like-minded districts.


Polarization has immense implications for political gridlock, party messaging, and attempts to be bi-partisan. On the one hand, the large number of ‘safe districts’ reduced interests in reaching across the aisle; on the other hand, fewer swing-vote representatives will mean that overcoming political gridlock will require reaching across the aisle. The poster-child of political gridlock is California, which both requires a super-majority to pass budgets or raise taxes but also has a proposition system which makes it easy to tie legislature’s hands. Political gridlock is particularly bad especially for looming issues, such as the economy, healthcare reform, and the deficit.

Average: 3 (1 vote)


RAND, Oct 2010, page 6: http://newsletters.clearsignals.org/RAND_Oct2010.pdf

Keith T. Poole and Howard Rosenthal, Ideology & Congress, (New Brunswick, Conn.: Transaction Publishers, 2007); Keith T. Poole, Spatial Model of Parliamentary Voting, (Cambridge and New York: Cambridge University Press, 2005).

Thomson, James A., 2010. A House Divided: Polarization and Its Effect on RAND, (Santa Monica.: RAND Corporation, 2010). Available at http://www.rand.org/pubs/occasional_papers/2010/RAND_OP291.pdf

Bill Bishop, Robert G. Cushing, The Big Sort: Why the Clustering of Like-Minded America Is Tearing Us Apart, (Boston: Houghton Mifflin, 2008).