PS: Political Science & Politics


New Support for the Big Sort Hypothesis: An Assessment of Partisan Geographic Sorting in California, 1992–2010

Jesse Sussell

RAND Corporation/Pardee RAND Graduate School


This article empirically examines the “Big Sort hypothesis”—the notion that, in recent years, liberal and conservative Americans have become increasingly spatially isolated from one another. Using block group-, tract-, and county-level party registration data and presidential election returns, I construct two formal indices of segregation for 1992–2010 in California and evaluate those indices for evidence of growth in the segregation of Californians along ideological lines. Evidence of rising geographic segregation between Democrats and Republicans for measures generated from both party registration and presidential vote data is found. This growth is statistically significant for 10 of the 12 segregation measures analyzed. In addition, many of the increases are practically significant, with estimates of growth in segregation during the observation period ranging from 2% to 23%.

Jesse Sussell is an assistant policy analyst at the RAND Corporation and a doctoral fellow at the Pardee RAND Graduate School. He is currently completing a dissertation there on the connection between mass and elite polarization in the United States; his other research focuses on the evaluation of novel criminal justice interventions. He can be contacted at