As states have diverged in their relative demand for skilled workers, the children born in these states have also diverged in their probability of graduating from college. We ask how much of this spatial divergence in college attainment can be explained by the growing differences in the types of people who live in these locations, or by the increased importance of frictions to geographic mobility, such as migration costs and out-of-state tuition. First, using panel data on individual education choices and college characteristics, we show that children are less likely to go to college when they are located in a labor market, at age 17, with a lower skill premium and lower access to quality colleges. Second, we build a dynamic spatial equilibrium model with college choice, financial frictions, migration, and endogenous heterogeneity across locations in the higher-education system. We calibrate the model and show how a spatially uneven skill-biased technical change shock can reproduce most of the observed divergence in college attainment. We find that migration costs, rather than financial constraints, out-of-state tuition, differences in college quality, or increased sorting, is most important for explaining the growing gap in college attainment.