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Political Parties as Drivers of U.S. Polarization: 1927-2018


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Moynihan Institute of Global Affairs 

Trade, Development and Political Economy presents 

Political Parties as Drivers of U.S. Polarization: 1927-2018

The current polarization of elites in the U.S., particularly in Congress, is frequently ascribed to the emergence of cohorts of ideologically extreme legislators replacing moderate ones. The authors present a multi-dimensional voting model and identification strategy designed to decouple the ideological preferences of lawmakers from the control exerted by their party leadership. Applying this structural framework to the U.S. Congress between 1927- 2018, they find that the influence of leaders over their rank-and-file has been a growing driver of polarization in voting, particularly since the 1970s. 

Francesco Trebbi 


University of California - Berkeley

Bernard T. Rocca Jr. Chair 

Francesco Trebbi is the Bernard T. Rocca Jr. Chair and Professor at the University of California, Berkeley Haas School of Business and Research Associate at the National Bureau of Economic Research.  His main area of research is political economy. More specifically, he works on political institutions and their design, elections and political campaigns, behavior in legislatures, campaign finance, lobbying, banking and regulation, political economy of development, corruption, ethnic politics, and intra-state conflict. He has several publications in top general-interest economics journals.

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