Voter migration as a source of electoral change in the Rocky Mountain West

Examining county-level voting patterns since 1992, this paper describes the rising strength of the Democratic Party in the Rocky Mountain West and explores domestic migration (voter mobility) as a cause of the electoral change. Other theories of electoral change (voter conversion, voter mobilization and generational replacement) are analyzed and found less significant than a voter migration theory. A spatial autoregressive model also presents evidence of significant contextual “neighborhood effects” contributing to electoral change in the region. Relying on IRS tax-filer migration data, Census data and voting results for all Western counties since 1992, this work finds a significant correlation between growing Democratic strength and in-migration of new voters who generally hail from more Democratic environments than the Western counties into which they are emigrating. The strongest correlations emerge in counties where the share of creative class occupations is also growing quickly. Migrating voters are building a new Western community – a community of creative classes, childless households and urban professionals who are more likely to vote Democrat than the rural conservatives they are increasingly outnumbering.