In the past 15 years, the adoption of subnational immigration policies in the United States, such as those established by individual states, has gone from nearly zero to over 300 per year. These include welcoming policies aimed at attracting and incorporating immigrants, as well as unwelcoming policies directed at denying immigrants access to public resources and services. Using data from a 2016 random digit-dialing telephone survey with an embedded experiment, we examine whether institutional support for policies that are either welcoming or hostile toward immigrants differentially shape Latinos' and whites' feelings of belonging in their state (Arizona/New Mexico, adjacent states with contrasting immigration policies). We randomly assigned individuals from the representative sample (n = 1,903) of Latinos (US and foreign born) and whites (all US born) to consider policies that were either welcoming of or hostile toward immigrants. Across both states of residence, Latinos, especially those foreign born, regardless of citizenship, expressed more positive affect and greater belonging when primed with a welcoming (vs. hostile) policy. Demonstrating the importance of local norms, these patterns held among US-born whites, except among self-identified politically conservative whites, who showed more negative affect and lower levels of belonging in response to welcoming policies. Thus, welcoming immigration policies, supported by institutional authorities, can create a sense of belonging not only among newcomers that is vital to successful integration but also among a large segment of the population that is not a direct beneficiary of such policies-US-born whites.