Brazil and the United States underwent a dramatic transformation in the nineteenth century: from the largest slaveholding polities in the hemisphere, both became bustling immigrant societies by century’s end. Historians have long and productively reflected on each country’s respective trend from slaving to immigrant society through the prism of social and economic history, underlining the mutually constitutive relationship between on-the-ground dynamics and migration regulations. However, these social histories often stop short of historicizing the production itself of migration policies, their deep embeddedness in the institution of slavery, and their mutually constitutive relationship with emergent national politics. Moreover, historical inquiries on the ties between slavery and immigration tend to remain within national bounds, precluding potential comparisons and connections between similar case studies. This roundtable takes recent scholarship as an opportunity to reexamine the possibilities opened up by a migration history focused on the production of policies and statutory regulations as part of a wider political history. Presenters will examine migration policy development in the United States and Brazil in comparative perspective, taking the two largest independent countries and last slave societies of the Americas as exemplars of the transnational dissemination of policy debates, regulatory models, and migration dynamics that defined migration preferences and restrictions, and brought together labor and mobility regimes variously informed by Black enslavement, free or "spontaneous" immigration, and Chinese labor during and after the coolie trade.