Essays on international migration

International migration happens because individuals want to increase their personal welfare by moving to a new country. In addition, it has effects on the welfare of those who decide not to migrate and remain in their origin countries. This dissertation looks at the overall topic of international migration from three very different angles: who the migrants are or the study of the productive characteristics of migrating individuals with respect to non-migrants; what the long run effect of migration is and specifically whether it can contribute to Social Security sustainability; and, finally, why countries sign bilateral migration agreements to try to regulate migration flows.;In Chapter 1, we examine the extent to which Mexican emigrants to the United States are negatively selected, that is, have lower skills than individuals who remain in Mexico. Previous studies have been limited by the lack of nationally representative longitudinal data. This one uses a newly available household survey, which identifies emigrants before they leave and allows a direct comparison to non-migrants. I find that, on average, US bound Mexican emigrants from 2000 to 2004 earn a lower wage and have less schooling years than individuals who remain in Mexico, evidence of negative selection. This supports the original hypothesis of Borjas (AER, 1987) and argues against recent findings, notably those of Chiquiar and Hanson (JPE, 2005). The discrepancy with the latter is primarily due to an under-count of unskilled migrants in US sources and secondarily to the omission of unobservables in their methodology.;Chapter 2 investigates fiscal sustainability in an overlapping generations economy with endogenous growth coming from human capital formation through educational spending. We assess how budgetary imbalances affect economic dynamics and the outlook for economic growth, thereby providing a rationale for fiscal rules ensuring sustainability. Our results show that the appropriate response of fiscal policy to temporary shocks is not trivial in the absence of fiscal rules. Fiscal rules allow for a timely reaction, thereby avoiding possibly disruptive fiscal adjustment in the future: the more adjustment is delayed, the larger its necessary scale is. We perform a rough calibration of the model to simulate the effects of a demographic shock (change in the population growth rate) under different fiscal policy scenarios. The demographic shock can also be interpreted as a change in the immigration rate so that the model can be used to study the effects of immigration on key macroeconomic variables in a partial equilibrium setting. It is partial equilibrium in the sense that immigrants do not respond to wage differential but are modeled as an exogenous shock instead.;Chapter 3 explains how unilateral migration policies impose externalities on other countries. In order to try to internalize these externalities, countries sign bilateral migration agreements. One element of these agreements is the emphasis on enforcing migration policies: immigrant-receiving countries agree to allow more immigrants from their emigrant-sending partner if they cooperate in enforcing their migration policy at the border. I present a simple theoretical model that justifies this behavior by combining a two country, two-good classical Ricardian model with welfare maximizing governments. These governments establish migration quotas that need to be enforced at a cost (modeled according to Ethier, 1986). I prove that Nash unilateral migration policies are inefficient whereas both countries can improve welfare by exchanging a more "generous" migration quota or terms of trade advantages for expenditure on enforcement policy. Contrary to what it could be expected, this result does not depend on the enforcement technology that both countries employ. The Ricardian assumption is not crucial either and a generalization of the model is introduced.