The paradox of rural depopulation and built-up growth: Insights from two decades of settlement change in China (2000–2020)

China’s rapid urbanization has triggered profound changes in its rural landscape. Despite ongoing rural depopulation, rural settlement areas continue to expand, often in an uncoordinated and inefficient manner. This study examines the spatial and temporal dynamics of rural settlement change in China from 2000 to 2020 at the township level and investigates the associated factors. Using a spatiotemporal distribution-driven framework, we integrate land use data, climatic and environmental variables, socio-economic indicators, and geographic accessibility measures. The XGBoost, combined with SHAP, was utilized to identify and interpret the complex, nonlinear relationships between rural settlement change and its influencing factors. Results show that rural settlements expanded by 14.08% over the 20 years, with 23,984 townships experiencing expansion and 9951 facing reduction. Notably, 1010 townships saw rural settlements vanish completely. Expansion clustered in the developed southeast during moderate periods, shifting northeast and west in active phases, mainly consuming cropland and some ecological land; reductions were dispersed. Natural environmental factors exert the most substantial influence on rural settlement changes. Expansion intensity was also greater in places farther from existing cropland, suggesting that non-farming drivers were spurring growth. Conversely, drastic settlement decline was strongly linked to nighttime light, underscoring the powerful pull of urbanization. This study highlights the mismatch between rural population trends and land consumption, revealing risks to both food security and environmental sustainability, and proposes differentiated strategies for rural restructuring tailored to local conditions. The findings guide policymakers seeking to optimize rural settlement patterns, support rural revitalization, and foster more sustainable land use.