Cities, Heterogeneous Firms, and Trade

Does international trade affect the growth of cities, and vice versa? Assembling disaggregate data for four countries, we document a novel stylized fact: Export activity is disproportionately concentrated in larger cities – even more so than overall economic activity. We rationalize this fact by marrying a standard quantitative spatial economics model with a heterogeneous firm model that features selection into the domestic and the export market. Our model delivers novel predictions for the bi-directional interactions between trade and urban dynamics: On the one hand, trade liberalization shifts employment towards larger cities, and on the other hand, liberalizing land use raises exports. We structurally estimate the model using data for the universe of Chinese manufacturing and French firms. We find that trade policies have quantitatively meaningful impacts on urban outcomes and vice versa, and that the aggregate effects of trade and urban policies differ from more standard models that do not account for the interaction between trade and cities. In addition, a distinguishing prediction of our model – which we confirm in the data – is that local trade elasticities vary systematically with city size, so that a country's aggregate trade elasticity depends on the spatial distribution of production within its borders.