Geographic Sorting in the Golden State, 1990-2014 : Evidence from County-level Data on Statewide Elections

Abstract

This paper addresses the question of partisan geographic sorting in California since 1990 and analyzes how the Golden State is geographically sorted along the party line. By applying an alternative way of measuring spatial division in vote choice across different counties, we analyze the vote shares data in California since 1990 and the findings suggest that Californian voters have become more clearly sorted along the party line across counties. According to the findings, red counties became more Republican, and the blue counties became more Democratic while the number of swing counties has declined. Further, this study suggests that geographic partisan sorting in California is mainly driven by the Swing counties whose median household income tends to be lower than the state average. Namely, we find that county level economic conditions are somehow associated with the changes in partisan vote choice, although further examination is required.