International migration reallocates labor from low-wage to high-wage economies, benefiting migrants and receiving countries but creating selection (high-ability emigrate) and skill-drain risks for sending countries. Remittances supplement household income in sending countries and now exceed official aid. Internal migration (rural-to-urban) drives urbanization and structural transformation; quality of urban institutions determines whether migrants thrive or end in slums.
Migration — both within and across national borders — is one of the most powerful forces in economic development. From your study of the demographic transition, you know that developing countries experience rapid population growth as death rates fall before birth rates adjust. This population pressure, combined with limited rural opportunities, creates strong incentives for people to move. Understanding migration's effects on development requires thinking about who moves, what they send back, and what happens to the places they leave and the places they arrive.
International migration moves workers from low-wage to high-wage economies, and the wage gains are enormous — often a 3x to 10x increase for the same worker doing the same job in a richer country. But migration is not random. It is selective: migrants tend to be younger, healthier, more educated, and more entrepreneurial than those who stay behind. This selection creates a tension. The migrant benefits individually, and the receiving country gains a productive worker. But the sending country loses some of its most capable people — the phenomenon known as brain drain. When a country that invested in training a doctor or engineer loses that person to a wealthier nation, the return on that educational investment is captured abroad. However, brain drain is not the whole story. Migrants who return bring skills, networks, and capital. And diaspora communities create trade and investment links between sending and receiving countries.
The most concrete channel through which migration benefits sending countries is remittances — money migrants send home to families. Global remittance flows to developing countries now exceed $600 billion annually, dwarfing official development aid. For many countries (Nepal, Haiti, Tajikistan), remittances constitute over 20% of GDP. At the household level, remittances reduce poverty, fund education, improve nutrition, and provide a buffer against income shocks. At the national level, they provide foreign exchange and stimulate local demand. But remittances also have limitations: they flow to households rather than public investment, they can create dependency, and they may appreciate the local currency, making exports less competitive.
Internal migration — particularly rural-to-urban movement — is the engine of structural transformation within countries. As workers move from low-productivity agriculture to higher-productivity urban employment, national output rises. This is the Harris-Todaro model in action: migrants compare expected urban wages (adjusted for the probability of finding employment) against certain rural wages, and move when the urban option looks better. The challenge is that urbanization can outpace the creation of formal jobs and adequate infrastructure. When cities cannot absorb migrants with productive employment and basic services — housing, sanitation, transport — the result is informal settlements, underemployment, and urban poverty. Whether migration drives development or merely relocates poverty depends critically on urban governance: cities with functioning land markets, infrastructure investment, and accessible public services turn migrants into productive citizens; cities without these institutions trap them in slums.