Decoding China’s urban transformation: Multiscale analysis of urban spatial structures and their influencing factors (2007–2023)

Investigating urban spatial structures (USSs) and their influencing factors at different spatial scales is crucial for promoting sustainable urban transformation. Based on nighttime light datasets and the Herfindahl–Hirschman index (HHI), this study analyzes USS characteristics in China from 2007 to 2023 on two spatial scales—prefecture-level cities and urban agglomerations. It also explores structural influencing factors, including the economy, infrastructure, society, and government intervention. We find that: (1) HHI values for both cities and urban agglomerations exhibit a decreasing trend, indicating a USS for both that is evolving toward polycentricity; (2) economic development promotes a polycentric structure at both spatial scales, whereas government intervention drives a monocentric structure; and (3) postal and communication infrastructure have conflicting effects on USSs, encouraging a monocentric structure at the city scale but fostering polycentricity at the urban agglomeration scale.