Immigration, Political Ideologies and the Polarization of American Politics

Talk by Johannes Matzat (University of Lucerne) as part of the Research Seminar Series of the IOS Economics Department.

We provide causal evidence that immigration has contributed to the polarization of American politics. Using an ancestry-based shift-share instrument, we examine immigration flows between 1992 and 2016 and demonstrate that counties with larger immigration inflows had more polarized campaign contributions in U.S. House of Representatives elections. Winners of elections become more polarized. The effects are particularly pronounced in primary elections, when moderate Democrats are more likely to lose and conservative Republicans are more likely to win in counties with larger immigration inflows. The rightward shift is strongest in immigrant-intensive occupations with limited direct contact with migrants. Candidates who emphasize immigration perform worse when they are liberal, while conservative Republicans gain disproportionately. We complement these findings with original survey data that illuminate the underlying mechanisms: liberals tend to emphasize the opportunities that immigration provides, while conservatives emphasize the risks. Reactions at both ideological extremes are amplified by variation in contact with immigrants.