The dynamics of mass migration

We specify a set of equations defining a dynamic model of international mig ration and estimate its parameters by using data specially collected in Mex ico, We then used it to project the a hypothetical Mexican community popula tion forward in time. Beginning with a stable population of 10,000 people, we project ahead 50 years under three different assumptions: no internation al migration; constant probabilities of in- and out-migration, and dynamic schedules of out- and in-migration that change as migratory experience accu mulates, This exercise represents an attempt to model the self-feeding char acter of international migration noted by prior observers and theorists. Ou r model quantifies the mechanisms of cumulative causation predicted by soci al capital theory and illustrates the shortcomings of standard projection m ethodologies. 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 p opulation living in the United States.