Cities and Countries

If one ranks cities by population, the rank of a city is inversely related to its size, a well-documented phenomenon known as Zipf’s Law. Further, the growth rate of a city’s population is uncorrelated with its size, another well-known characteristic known as Gibrat’s Law. In this paper, I show that both characteristics are true of countries as well as cities; the size distributions of cities and countries are similar. But theories that explain the size distribution of cities do not obviously apply in explaining the size distribution of countries. The similarity of city- and country-size distributions is an interesting riddle.