In their recent Washington Post article, Morris P. Fiorina of Stanford University and Samuel Abrams of Sarah Lawrence College discuss the widespread claim that the American electorate has become increasingly polarized.

Fiorina and Abrams explain that, while the US political class has become demonstrably polarized, there is little evidence that today's electorate is substantially different from what it was in the 1970s.  Both partisanship and self-identified ideology appear to have fluctuated modestly within a narrow range, and opinion distributions retain a centrist shape with no indication of a shift toward the poles.



What did change, however, is the sorting of partisan sub-groups within the larger population (i.e., the distribution of partisans in terms of their ideology and issue opinions): "Self-identified Democrats have become more homogeneously liberal and self-identified Republicans more homogeneously conservative. And the differences between the two partisan groups on issues have increased, although not nearly as much as those among party elites. For example, ordinary Democrats and Republicans were indistinguishable on abortion until the 1990s and then began to differ (as the figure below illustrates), but even in 2012, American National Election Study data indicate that a quarter of Democrats arguably fall into the pro-life category and a third of Republicans into the pro-choice category."