Migration Costs, Sorting, and the Agricultural Productivity Gap

We use a unique panel dataset and a policy experiment as an instrument to estimate the impact of policy-induced migration cost reductions on rural-to-urban migration and the associated increase in labor earnings for migrant workers in China. Our estimation shows that there exist both large migration costs and a large underlying productivity difference between rural agricultural and urban non-agricultural sectors in China. More than half of the observed labor earnings gap between the two sectors can be attributed to the underlying productivity difference, and less than half of the gap can be attributed to sorting of workers. We also structurally estimate a general equilibrium Roy model and use it to quantify the effects of reducing migration costs on the observed sectoral productivity difference, migration, and aggregate productivity. If we implement a hukou policy reform by setting the hukou liberalization index in all regions of China to the level of the most liberal region, the observed agricultural productivity gap would decrease by more than 30%, the migrant share would increase by about 9%, and the aggregate productivity would increase by 1.1%. In contrast, in a partial equilibrium in which the underlying productivity difference does not change with migration cost, the hukou policy reform would reduce the observed agricultural productivity gap by only 9%, the migrant share would increase by more than 50%, and the aggregate productivity would increase by 6.8%.