Cross-Country Trends in Affective Polarization Levi Boxell, Stanford University∗ Matthew Gentzkow, Stanford University and NBER Jesse M. Shapiro, Brown University and NBER August 2021 Abstract We measure trends in affective polarization in twelve OECD countries over the past four decades. According to our baseline estimates, the US experienced the largest increase in po- larization over this period. Five countries experienced a smaller increase in polarization. Six countries experienced a decrease in polarization. We relate trends in polarization to trends in potential explanatory factors concerning the economy, technology, demography, and politics. keywords: comparative politics, mass polarization, news media, ethnic fractionalization JEL codes: D72, O57 ∗E-mail:
[email protected],
[email protected], jesse shapiro
[email protected]. We thank James Adams, Klaus Desmet, John Duca, Ray Fair, Morris Fiorina, Greg Huber, Shanto Iyengar, Emir Kamenica, Rishi Kishore, Yphtach Lelkes, Matthew Levendusky, Neil Malhotra, Greg Martin, Eoin McGuirk, Pippa Norris, Carlo Schwarz, Sean Westwood, and seminar participants at the DC Political Economy Center Webinar, Stanford University, the Brown Data Science Initiative, the CREST Reading Group on Political Economy, and the American Economic Association for their comments and suggestions. We thank Lenka Drazanova and Philipp Rehm for sharing data, Dina Smeltz for sharing survey questionnaires, Rune Stubager for providing questionnaire translations, Will Horne for assistance with the CSES data, and Marc Swyngedouw for answering inquiries about the Belgium National Election Study. We also thank our many dedicated research assistants for their contributions to this project. We acknowledge funding from the Population Studies and Training Center, the Eastman Professorship, and the JP Morgan Chase Research Assistant Program at Brown University, the Stanford Institute for Economic Policy Research (SIEPR), the Institute for Humane Studies, the John S.