An abstract spectrum of blue and red colors.

Working Paper

The Changing Polarization of Party Ideologies: The Role of Sorting

February 2024

WP 24-04 – History shows that when political parties become more polarized along one dimension of policy, they become less polarized along some other dimension. We explain how this can happen via changes in the ideological make up parties.

Supersedes Working Paper 23-07 – The Changing Polarization of Party Ideologies: The Role of Sorting

Ideology scores derived from U.S. congressional roll-call voting patterns show that the ideological distance between the two parties along the primary dimension changes inversely with the ideological distance along the secondary dimension. To explain this inverse association, a model of party competition with endogenous party membership and a two-dimensional ideology space is developed. If the distribution of voter preferences is uniform on a disk, equilibrium ideological distances along the two dimensions are inversely related. The model can quantitatively account for the historical movements in ideological distances as a function of changes in the ideological orientation of the two parties.

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Polarized Contributions but Convergent Agendas

September 2022

WP 22-29 – The political process in the United States appears to be highly polarized: Data show that the political positions of legislators have diverged substantially, while the largest campaign contributions come from the most extreme donor groups and are directed to the most extreme candidates.

The Economy

Working Paper

Partisan Conflict

Marina Azzimonti

June 2014

WP 14-19 – American politics have become extremely polarized in recent decades. This deep political divide has caused significant government dysfunction.