More agglomerations, more polarization? Urban development during the last 20 years in China

Abstract Urban polarization, characterized by differences in city-size distribution, is underway in China, wherein the government aims to promote coordinated development among cities of different sizes based on urban agglomerations. This study explored the spatial-temporal characteristics of urban area expansion of 23 urban agglomerations in China and assess the city-size change within the agglomerations by the urban primacy index and Pareto exponent. The urban area extent within these 23 UAs increased by 280.90% in the study period. Coastal urban agglomerations were larger in size and maintained a relatively high annual growth rate compared to inland agglomerations, indicating a more polarized pattern. Changes within the agglomerations resulted in less polarization given that the urban primacy and Pareto exponent inside most UAs decreased. Policies implemented to achieve enhanced urbanization coordination in China appear to be partially successful, but the polarization process remains hard to break due to the complexities of the process.