Contagious Collectivities: On the Spatial Diffusion of Swedish Trade Unions, 1890-1940

This article how distances and relations between actors are likely to influence the growth and spread of social movements. A formal theoretical model is developed that extends previous work on threshold models of collective behavior. Spatial distribution of a population influences the network that are likely to emerge within the population; these network, in turn, will influence the likely outcome of a mobilization effort. Key theoretical predictions are tested using data on the founding of local union organizations in Sweden, 1890-1940. The empirical analyses show that contagious spatial processes were of considerable importance for the growth of the Swedish union movement, thus supporting the theoretical argument. The analyses presented in the article provide an alternative interpretation of density-dependent founding rates to the one offered by organizational ecologists.