Clustering and expected seat-share for district maps

Abstract

In the context of modern sampling methods for redistricting, we define a natural measurement of the clustering of a political party, and we study how clustering affects the expected election outcome. We first prove general results and then apply this framework to understand how the political geography in Pennsylvania affects the expected outcome of congressional elections.

Keywords:

• Redistricting; clustering; gerrymandering

Acknowledgments

The author is pleased to thank Paul Klingsberg and the referee for valuable feedback.