A new economic geography model of central places

One of the most striking feature of the space-economy is that cities form a hierarchical system exhibiting some regularity in terms of their size and the array of goods they supply. In order to show how such a hierarchical system may emerge, we consider a model with monopolistically competitive markets for the industrial sectors. As transport costs steadily decrease from large values, the urban system formed by several small cities entails structural changes in that some cities expand at the expense of the others by attracting a growing number of industries. Beyond some threshold, some cities disappear from the space-economy. Such an evolution of the urban system describes fairly well what has been observed in various historical periods that have experienced major changes in transportation technologies and/or political unification.