We study the internal organization of French manufacturing firms. We divide the employees of each firm into “layers” using occupational categories. Layers are hierarchical in that the typical worker in a higher layer earns more, and the typical firm occupies less of them. The probability of adding/dropping a layer is positively/negatively correlated with value added. Reorganization, through changes in layers, is essential to understanding how firms grow. Firms that expand substantially add layers and pay lower average wages in all preexisting layers. In contrast, firms that expand little and do not reorganize pay higher average wages in all preexisting layers.

To understand the elasticity of employment to local labor demand shocks, we develop a quantitative general equilibrium model that incorporates spatial linkages in goods markets (trade) and factor markets (commuting and migration). We show that local employment elasticities differ substantially across U.S. counties and commuting zones in ways that are not well explained by standard empirical controls but are captured by commuting measures. We provide independent evidence for these predictions from million dollar plants and find that empirically-observed reductions in commuting costs generate welfare gains of around 3.3 percent and employment reallocations from -20 to 30 percent.