City size dynamics in urban systems

International audienceSystems of urban settlements are characterized by their hierarchical organization. The empirical observation of a large set of cities over almost two centuries shows that this hierarchy evolves very slowly, despite the rapid fluctuations in the growth of individual cities. We suggest developing a theory of the evolution of urban systems, which would connect the slow dynamics of their city-size distribution with the more rapid dynamics of the individual cities competing for attracting the populations. Both dynamics are shown to be related to the spatial properties of urban systems