The Polarization of American Politics

Elected officials in the United States appear to represent relatively extreme support coalitions rather than the interests of middle-of-the-road voters. This contention is supported by analysis of variance of liberal-conservative positions in the United States Senate from 1959 to 1980. Within both the Democratic and the Republican parties, there is considerable variation in liberal-conservative positions, but two senators from the same state and party tend to be very similar. In contrast, two senators from the same state but from different parties are highly dissimilar, suggesting that each party represents an extreme support coalition in the state. Moreover, the distribution of senators is now consistent with the hypothesis that, in the long run, both parties are equally likely to win any seat in the Senate. This result suggests that there is now competition between equally balanced but extreme support coalitions throughout most of the United States.