Agglomeration or Selection? The Case of the Japanese Silk-Reeling Clusters, 1908-1915

We examine two sources of productivity improvement in the specialized industrial clusters of the early twentieth century Japanese silk-reeling industry. Agglomeration improves the productivity of each plant through positive externalities, shifting plant-level productivity distribution to the right. Selection expels less productive plants through competition, truncating distribution on the left. We find no evidence confirming a right shift in the distribution in clusters or that agglomeration promotes faster productivity growth. Rather, the distribution in clusters was severely left truncated, even for younger plants. These findings imply that the plant-selection effect was the source of higher productivity in the Japanese silk-reeling clusters.