"This paper proposes a simple theory of a system of cities that decomposes the determinants of the city size distribution into three main components: efficiency, amenities, and frictions. Higher efficiency and better amenities lead to larger cities, but also to greater frictions through...

There is a large literature on the existence of agglomeration economies, as shown in the surveys by Moomaw (1983) or Gerking (1993). The benefits of these economies arise from multiple sources, but some negative externalities might also emerge. Within the hierarchical urban system, cities at...