Migration, Specialization, and Trade: Evidence from Brazil's March to the West

Exploiting a large migration of farmers to the West of Brazil between 1950 and 2010, we study how migration shapes aggregate and regional comparative advantage. We document that farmers emigrating from regions with high employment in an activity are more likely to work in that activity and have higher income than other migrants doing so. We incorporate this heterogeneity into a quantitative model and find that, by reshaping comparative advantage, declines in migration costs contributed substantially to Brazil's rise as a leading commodity exporter. Opportunities to migrate, moreover, account for a substantial share of the gains from trade.