Abstract
Available data have consistently pointed up the failure of U.S. policies to reduce undocumented migration from Latin America. To shed light on the reasons for this failure, we estimated a series of dynamic models of undocumented entry into and exit from the United States. Our estimates suggest that undocumented migration is grounded more in mechanisms posited by social capital theory and the new economics of labor migration rather than neoclassical economics. As a result, U.S. efforts to increase the costs of undocumented entry and reduce the benefits of undocumented labor have proven unsuccessful given the widespread access of Latin Americans to migrant networks. The main effect of U.S. enforcement efforts has been to reduce the circularity of Latin American migration.