The Dynamics of Mass Migration

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 96; no. 9; pp. 5328 - 5335
• Main Authors: Massey, Douglas S., Zenteno, Rene M.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 27.04.1999; National Acad Sciences; National Academy of Sciences; The National Academy of Sciences
• Series: Inaugural Article
• Subjects: Communities; Demography; Emigration and Immigration; Human migration; Humans; International migration; Labor migration; Mexican Americans; Mexico; Migrant communities; Migration; Models, Statistical; Population dynamics; Population Growth; Population migration; Population size; Return migration; Social capital; Social research; Social Sciences; United States; United States; Mexico
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.96.9.5328

We specify a set of equations defining a dynamic model of international migration and estimate its parameters by using data specially collected in Mexico. We then used it to project the a hypothetical Mexican community population forward in time. Beginning with a stable population of 10,000 people, we project ahead 50 years under three different assumptions: no international migration; constant probabilities of in- and out-migration, and dynamic schedules of out- and in-migration that change as migratory experience accumulates. This exercise represents an attempt to model the self-feeding character of international migration noted by prior observers and theorists. Our model quantifies the mechanisms of cumulative causation predicted by social capital theory and illustrates the shortcomings of standard projection methodologies. The failure to model dynamically changing migration schedules yields a 5% overstatement of the projected size of the Mexican population after 50 years, an 11% understatement of the total number of U.S. migrants, a 15% understatement of the prevalence of U.S. migratory experience in the Mexican population, and an 85% understatement of the size of the Mexican population living in the United States.