Historians have well described how US immigration policy increasingly fell under the purview of federal law and national politics in the mid-to-late nineteenth century. It is far less understood that the rights of noncitizen immigrants in the country remained primarily contested in the realms of state politics and law until the mid-to-late twentieth century. Such state-level political debates often centered on whether noncitizen immigrants should vote, count as part of the polity for the purposes of state legislative representation, work in public and publicly funded employment, or obtain professional licensure. Enacted state alienage laws were rarely self-executing, and immigrants and their allies regularly challenged nativist restrictions in court, on the job, by appealing to lawmakers and the public, and even via diplomacy. Battles over the passage, implementation, and constitutionality of such policies at times aligned with and sometimes clashed against contemporaneous efforts to expand rights to marginalized Americans, particularly US-born women. Often considered separately or treated as topics of marginal importance, Disparate Regimes underscores the centrality of nativist state politics and alienage policies to the history of American immigration and citizenship from the late nineteenth to the mid-twentieth centuries. It argues that the proliferation of these debates and laws produced veritable disparate regimes of citizenship rights in the American political economy on a state-by-state basis. It further illustrates how nativist state politics and alienage policies helped to invent and concretize the idea that citizenship rights meant citizen-only rights in law, practice, and popular perception in the United States.