A large body of literature studies how infrastructure facilitates trade. We ask whether infrastructure also facilitates migration. Using a general equilibrium trade model and rich spatial data, we study the impact of a large, plausibly exogenous shock to highways in Brazil on both goods and labor markets. We find the highway system increased welfare by 2.8 percent, of which 76 percent was due to reduced trade costs and 24 percent to reduced migration costs. An implication of costly migration is spatial heterogeneity in benefits: the range of welfare improvement is 1 to 15 percent, as opposed to uniform gains with perfect mobility. (JEL H54, H76, O18, R23, R42, R53)