On a sustained basis, cities are of non-uniform relative sizes. This paper addresses three basic issues which arise from this simple observation by examining the size distribution of US cities over the period 1900--1990. First, we explore the reasons why there is a wide distribution of city...

This paper models and examines empirically the evolution of cities in an economy. Twentieth century evolution in the USA is characterized by parallel growth of cities of different types and on-going entry of new cities, together maintaining a stable relative size distribution of cities. Each...