The determinants of national city size distributions: A BMA approach

This paper investigates the factors that influence the national distribution of city sizes, using data from both gridded population estimates and nighttime lights. Leveraging a global definition of human settlements, it also accounts for spatial units smaller than traditional urban centers. To address model uncertainty in identifying robust determinants of cross-country variation in urban concentration, the analysis employs Bayesian model averaging techniques. Across different samples, openness to trade, the Polity score, and natural resource dependence consistently show posterior inclusion probabilities of approximately 50 % or higher. The findings highlight the potential roles of international trade and institutional quality in fostering more balanced national urban systems. • City size distribution determinants analyzed using global cross-country data. • City sizes estimated with both population and nighttime lights data. • Smaller settlements, not just major urban centers, are included in the analysis. • Bayesian model averaging used to identify robust city size distribution drivers. • Trade and institutional quality linked to more balanced urban systems.