Liberals and conservatives have mainly moved further apart on a wide variety of policy issues; the divergence is substantial quantitatively and in its plausible political impact: intra party moderation has become increasingly unlikely

Peltzman, Sam, Polarizing Currents within Purple America (August 20, 2018). SSRN: http://dx.doi.org/10.2139/ssrn.3235867

Abstract: The ideology of average Americans has changed little since the 1970s. Then as now around 30 percent identify liberal or conservative and 40 percent are moderates. In contrast to this stable “purple” distribution political parties have become more polarized into “red” and “blue” ideological camps with much less overlap than in the past. This paper contributes to the literature that seeks to reconcile these divergent trends by examining changes in the policy preferences within ideological categories. I analyze answers to a stable set of questions in the General Social Survey. The key finding is that liberals and conservatives have mainly moved further apart on a wide variety of policy issues. The divergence is substantial quantitatively and in its plausible political impact: intra party moderation has become increasingly unlikely.

Keywords: political polarization, political ideology, economic policy, social policy
JEL Classification: D72, D78