Social Bases of Partisanship
Cleavage Structures and Intersectional Bases

This paper explores the social bases of partisanship in the US. We identify two distinct ways in which partisanship can be embedded in existing social divisions: cleavage structures---capturing the depth and alignment of cleavages---and intersectional structures---highlighting the political relevance of unique combinations of group memberships. We discuss how these two forms of embeddedness have different implications for integration. Then, we develop analytical tools to distinguish them empirically, which entails a (1) decomposition approach to measure both the depth and alignment of cleavages and (2) a model that overcomes the sparsity problem in analyzing the partisanship of a large number of intersectional categories. Analyzing the General Social Survey from 1977 to 2022, we find that the depth of individual cleavages---especially race and religiosity---has increased over time. However, we also find increasing dealignment between cleavages, especially among the deepest ones, producing growing cross-pressures rather than consistent pressure towards either party. Furthermore, political identities are increasingly shaped at the intersection of social divisions. Our findings underscore the growing complexity of the social roots of partisanship in the US and call for a shift from examining single social divisions in isolation to analyzing the alignment of cleavages and intersections.