"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...

We consider whether external urban economic advantages (agglomeration economies) vary with time and space using a simple economic model and detailed micro-data on 134 locations in New Zealand for the period 1976-2018. We find subtle temporal variation, with estimates peaking in 1991 and then...