With comprehensive immigration reform dead for the foreseeable future, immigration laws enacted at the subfederal level -- cities, counties, and states -- have become even more important. Arizona has dominated media coverage and become the popular representation of the states' response to immigration by enacting SB 1070 and other notoriously anti-immigrant laws. Illinois, by contrast, has received relatively little media coverage for enacting laws that benefit the immigrants within its jurisdiction. The reality on the ground is that subfederal jurisdictions in the United States have taken very divergent paths on the issue of immigration regulation.

Compiling city, county, and state immigration laws from 2005-2011, we created a unique database that enables us to build the Immigrant Climate Index ("ICI"): a measure of the divergent immigration climates created by individual jurisdictions. The reasons for this divergence have received surprisingly little analysis; existing analysis has focused on the presence and effect of immigrants and the political ideology of the subfederal jurisdictions.

Our study demonstrates that there is another important factor to consider. Instead of looking outward to the foreign immigrants moving into a jurisdiction, we look inward and study the impact of domestic migrants (those who moved into a state from another state within the past year). Using panel regressions incorporating our ICI scores and census data, we observe that domestic migrants are affecting the immigration climate of their new home states. Domestic migrants are more likely to be educated and to be politically active, and thus to carry their immigration preferences to their new states. Specifically, domestic migrants coming from states with negative ICI scores have a negative effect on their new states' ICI scores. Moreover, the influence of domestic migrants is magnified, and more negative, when they move from states that are predominantly white, to states with large immigrant populations. Our results support a story of intergroup conflict, in which domestic migrants react negatively to the racial, ethnic, and cultural dislocation they experience in their new home states.