Red States vs. Blue States: Going Beyond the Mean

In recent years, many scholars have explored the degree of polarization between red and blue states (red states are those carried by Republicans at the presidential level; blue states are those carried by Democrats). Some claim that red- and blue-state citizens are deeply polarized, while others disagree, arguing that there are only limited differ- ences between the two groups. All previous work on this topic, however, simply uses difference-of-means tests to determine when these two groups are polarized. We show that this test alone cannot determine whether states are actually polarized. We remedy this shortcoming by introducing a new measure based on the degree of issue-position overlap between red- and blue-state citizens. Our findings demonstrate that there is only limited polarization—and a good deal of common ground— between red states and blue states. We discuss the implications of our work both for the study of polarization itself and for the broader study of American politics.