How Urban Agglomeration Policies Influence the Coordinated Regional Development of Population, Economy, and Environment : Insights from Three Premier Urban Agglomerations in China

Urban agglomeration policy is a critical indicator of China’s shift from urban autonomous development to regional integration. Given China’s relatively late start in agglomeration development, clarifying the policy’s relationship with population-economy-environment coordinated development (CDR-PEE) is essential for high-quality regional growth. This study takes three premier urban agglomerations in China Beijing-Tianjin-Hebei, Yangtze River Delta, and Chengdu-Chongqing as research objects, adopting a quasi-natural experiment and multi-period difference-in-differences (DID) model for empirical analysis. Results show the policy significantly promotes CDR-PEE, with obvious spatial heterogeneity: its effect varies by geographical positioning and the number of core cities. Mediation analysis identifies technological innovation and industrial structure upgrading as key transmission channels through which the policy drives CDR-PEE. Finally, relevant policy recommendations are proposed to provide insights for optimizing regional coordinated development strategies.