A typology of activities over a century of urban growth

Contemporary literature on the dynamics of economic activities in growing cities has mainly focused on time frames of a few years or decades. Using a new geohistorical database constructed from historical directories with about 1 million entries, we present a comprehensive analysis of the dynamics of activities in a major city, Paris, over almost a century (1829–1907). Our analysis suggests that activities that accompany city growth can be classified in different categories according to their dynamics and their scaling with population: (1) linear for everyday needs of residents (food stores, clothing retailers, health care practitioners), (2) sublinear for public services (legal, administrative, educational) and (3) superlinear for the city’s specific features (passing fads, specialization, timely needs). The dynamics of these activities is in addition very sensitive to historical perturbations such as large-scale public works or political conflicts. These results shed light on the evolution of activities, a crucial component of growing cities. Relationships among variables such as innovation and crime and the population sizes of cities are a cornerstone of urban science. This study creatively looks over time at how economic activities evolved as a single, iconic city, Paris, grew between 1829 and 1907.