From Fragmentation to Integration? How Globalization Reshaped the Global Urban Hierarchy, 1950–2030

ABSTRACT

The progressive integration of the world economy has gradually transformed urban hierarchies from a macro‐regional structure into a fully integrated global system. To examine this long‐run transition, we use the United Nations World Urbanization Prospects. Our analysis focuses on the 1860 global cities that had more than 300,000 inhabitants in 2018, whose population trajectories are traced over the period 1950–2030. We examine the well‐established size–rank relation first with OLS and then with Multiscale Geographically Weighted Regression (MGWR) to account explicitly for its spatial heterogeneity. Results show that, in 1950, OLS fits imperfectly, while MGWR substantially improves the estimates, suggesting that, at that time, this future‐selected cohort was structured around macro‐regions rather than functioning as a fully integrated global urban system. Adherence to Zipf's law strengthens over time and, with the advance of globalization, the urban hierarchy appears increasingly consistent with a single integrated global hierarchy. Moreover, a marked contraction in the dispersion of local slopes emerges. This suggests that local city‐size hierarchies have become more similar across space, a pattern consistent with increasing global integration. Departures from Zipf's law are also meaningful. In 1950, future OECD cities were oversized, whereas by 2020, capital cities and cities in OECD countries are associated with more negative MGWR local slopes, which we interpret as evidence of local departures from the global scaling pattern. Overall, the spatially explicit results of Zipf's law appear not as a stylized curiosity, but as an emergent equilibrium of integrated markets, while “where and why” it fails provides actionable signals for measurement and policy.