City Size Distribution across the OECD: Does the Cities Definition of Cities Matter?

This study provides new comparative evidence on city size distribution in OECD (the Organisation for EconomicCo-operation and Development) countries, by using consistently defined functional urban areas (FUAs). FUAs areidentified by an algorithm based on population density at grid level and commuting patterns and are thought tobetter approximate economic agglomerations and their internal spatial organisation. Results showthat Zipf's lawprovides a better description of city size distributionwhen cities are measured in terms of FUAs rather than usingtraditional administrative definitions. In addition, Zipf's law describes well city size distribution both at countrylevel andwider spatial scales, that is, by continent and for thewhole OECD. Finally, the power lawhypothesis – ofwhich Zipf's law is a particular case – was not rejected in most of the countries.