A dynamic general equilibrium model of migration is developed to explain the main
features of geographic mobility of workers across U.S. states. Models of net flows
only cannot explain the positive cross-sectional correlation between gross inflow and
outflow rates. The dynamics of migration flows is driven by local productivity shocks
and idiosyncratic shocks to the match between a worker and a location. The latter
is revealed only after migration has occurred. Thus, migrating workers have a higher
propensity to migrate again than incumbent workers and locations that attract high
numbers of migrants also tend to experience high outflow rates.