We test for an effect of Arizona’s 2007 Legal Arizona Workers Act (LAWA) on the proportion of the state population characterized as foreign-born, as non-citizen, and as non-citizen Hispanic. We use the synthetic control method to select a group of states against which the population trends of Arizona can be compared. We document a notable and statistically significant reduction in the proportion of the Arizona population that is foreign-born and in particular, that is Hispanic noncitizen. The decline observed for Arizona matches the timing of LAWA's implementation, deviates from the time series for the chosen synthetic control group, and stands out relative to the distribution of placebo estimates for the remainder of states in the nation. Furthermore, we do not observe similar declines for Hispanic naturalized citizens, a group not targeted by the legislation. Our results on LAWA's impact on the housing market provide further support for our findings.