Chain Migration Mapping

Chain migration mapping reconstructs the social mechanism by which one migrant's move triggers many others, tracing the kin, friend, and paesani ties along which earlier arrivals recruit and sponsor later ones into the same destination. John and Leatrice MacDonald's 1964 study of Italian migration to the United States gave the process its classic name, showing how chains of personal sponsorship channel newcomers into specific neighborhoods and produce the dense ethnic enclaves that dot immigrant cities. The method treats migration not as independent decisions by isolated individuals but as a self-feeding network in which each settler lowers the cost and risk of moving for those still at home. Douglas Massey's 1990 theory of cumulative causation formalized why such chains accelerate over time, as every new migrant expands the web of contacts that makes the next move easier. Mapping a chain therefore means building the directed sponsorship graph, ordering it by arrival time, and clustering it at the destination to reveal how neighborhoods crystallize. The result is both a descriptive map of who brought whom and an explanatory account of why migration streams persist and concentrate.