County-level assessment of coordinated relationship between land and population in urban China

Urban construction land (UCL) and urban population (UP) are two core indicators of urbanization, and their interaction reflects the quality of urban development. While most studies investigating this relationship have concentrated on provincial and city scales, systematic evidence at the county level remains limited, despite counties becoming increasingly important in China's new-type urbanization strategy. This gap hinders the identification of intra-provincial disparities and spatial interactions, thereby limiting the effectiveness of locally differentiated policy design. This study integrates satellite and statistical data to examine the spatiotemporal relationship between UCL and UP across counties in China and evaluates the coupling coordination degree (CCD) over the period 2000–2021 and its driving forces. The analysis shows that although both UCL and UP continued to expand, UP growth has consistently lagged behind UCL expansion. The CCD improved over time, and county-level values are lower than those at the provincial level. Notably, within provinces with high overall CCD, significant disparities exist among counties. Spatially, high-high (HH) clusters predominate in eastern counties, while low-low (LL) clusters emerge mainly in the northwestern and southwestern counties. Spatial econometric results further reveal that GDP and government revenue significantly enhance CCD through both direct effects and positive spatial spillovers, whereas industrial structure and public services produce negative spillover effects. This county-level analysis provides new evidence on spatial heterogeneity and spillover mechanisms, offering a more precise basis for optimizing resource allocation and advancing sustainable urban governance in China. • UP growth lagged behind UCL expansion, suggesting an imbalance in urban development. • The CCD improved over time, and county-level values are lower than those at the provincial level. • Within provinces with high overall CCD, large disparities exist among counties. • Economic, industrial, and public services in neighboring counties show spatial spillover effects.