Charting multidimensional ideological polarization across demographic groups in the United States

Abstract

Has ideological polarization actually increased in the last decades, or have voters simply sorted themselves into parties matching their ideology more closely? We present a novel methodology to quantify multidimensional ideological polarization, by embedding the respondents to a wide variety of political, social, and economic topics from the American National Election Studies (ANES) into a two-dimensional ideological space. By identifying several demographic attributes of the ANES respondents, we chart how political and socio-economic groups move through the ideological space in time. We observe that income and especially racial groups align into parties, but their ideological distance has not increased over time. Instead, Democrats and Republicans have become ideologically more distant in the last 30 years: Both parties moved away from the center, at different rates. Furthermore, Democratic voters have become ideologically more heterogeneous after 2010, indicating that partisan sorting has declined in the last decade.