Policy Divergence and Voter Polarization in a Structural Model of Elections

One of the most widely discussed phenomena in American politics today is the perceived increasing partisan divide that splits the U.S. electorate. A contested question is whether this diagnosis is actually true and, if so, what the underlying cause might be. We propose a new method that simultaneously estimates voters’ preferences and parties’ positions on economic and cultural issues. We apply the model to U.S. presidential elections between 1972 and 2008. The model recovers candidates’ positions from voters’ behavior and decomposes changes in the overall political polarization of the electorate into changes in the distribution of voters’ ideal positions (voter radicalization) and consequences of elite polarization (sorting).