Decomposing Spatial Polarization: The Political Demography of Presidential Elections in the United States

• In Event: Politics and Population Processes

Abstract

For the past decades, the United States has witnessed a continuing growth of political polarization that spans the political system, public opinion, interpersonal affection, as well as its geography. This paper introduces a decomposition framework that analyzes spatial polarization from a political demography perspective. By tracking changes in presidential election patterns and demographic compositions across U.S. counties and states since the 1990s, we document three key trends: a marked increase in the dispersion of local political climates, a growing association between local political climates and demographic structures, and heterogeneous trends of segregation across demographic factors. The decomposition analysis shows that demographic processes can account for a substantial share of the rising dispersion in political climates, with the strengthening linkage between demographics and politics playing a more central role. We conclude by discussing the implications of this deepening spatial polarization and the evolving entanglement between demography and democracy.

Author

• Peng Huang, University of Georgia