Recent Theoretical Paradigms in Urban Growth

The aim of this article is to present a critical view of the theoretical toolboxes developed in urban economics to explain urban city size. The article starts with the consideration that, during the 1960s and 1970s, the question of optimal city-size tended to be expressed in a misleading way. The real issue is not an “optimal city size” but an “efficient size”, which depends on the functional characteristics of the city and on the spatial organization within the urban system. Economies of scale exist up to a certain city size. However, urban development generates conditions leading to structural readjustments which lead to new economic advantages. These structural adjustments may be either sectoral transformations towards higher-order functions, or the emergence of external linkages with other cities. The article provides recent empirical evidence of the role played by urban functions and city networking in explaining urban equilibrium size. The empirical analyses reported here witness the importance of the structural adjustment of cities needed to achieve a higher equilibrium size.