By constructing an index system, this study analyzed the temporal and spatial characteristics of the economic resilience of 20 resource-based cities in northeast China after the financial crisis in 2008. On this basis, a mediation model was introduced to explore the mechanism of population shrinkage affecting economic resilience. The results show that: (a) from 2009 to 2019, the trend of the economic resilience of resource-based cities in northeast China was “ascending–descending–stable”. As time went by, the spatial difference of the economic resilience of resource-based cities gradually became obvious, indicating that the number of medium- and high-class cities was increasing. (b) By applying a correlation analysis, it was found that both a significant weak correlation and medium correlation existed between population shrinkage and economic resilience during the periods of 2011–2019 and 2013–2019. (c) Six mediation factors, namely industrial output, population consumption, resource dependence, urban innovation, cultural construction and environment quality, were chosen to apply the mediation model of population shrinkage affecting economic resilience. Among them, industrial output, population consumption, urban innovation, and cultural construction exerted a partial mediation effect on the process of population shrinkage affecting economic resilience, while the meditation effects of resource dependence and environment quality were not significant.

The impact of spatial structure on the Urban-Rural income gap varies across regions and scales. Much of the current literature focuses on urban agglomerations, highlighting the need for more in-depth exploration of specific regions. Using LandScan population data, this paper investigates urban spatial structure from the perspective of monocentricity and polycentricity, investigating their respective impacts and mechanisms on the Urban-Rural income gap in Northeast China. The findings are as follows: (1) The development of a monocentric spatial structure in Northeast China significantly reduces the Urban-Rural income gap, a conclusion verified through robustness testing. (2) A mediation effect test confirms that this spatial structure reduces the gap by increasing urban labor productivity. (3) The urban spatial structure of Northeast China also has positive spillover effects, reducing income inequality between urban and rural areas in neighboring regions. Further exploration of the relationship between Urban-Rural income inequality and spatial structure is crucial for achieving shared prosperity. Additionally, this research provides policy support for developing a novel framework for land use planning and conservation.

Against the backdrop of sustained population shrinkage, fine-grained and interpretable quantitative evidence on urban vitality and its built environment drivers remains limited. Taking Hegang, a typical shrinking city in China, as the study area, this study integrates Geographical-XGBoost (G-XGBoost) model with SHAP to identify the key determinants of daytime and nighttime vitality, to examine their nonlinear effects, and to compare the differentiated mechanisms under varying population change scenarios. The results show that Hegang exhibits a spatial pattern characterized by peripheral growth and central shrinkage, and population increase does not necessarily translate into higher urban vitality. Daily service facilities, road density, and population density emerge as the dominant factors shaping urban vitality. Most built environment variables display clear threshold ranges and diminishing marginal effects; for example, moderate population agglomeration and improvements in the road network could enhance urban vitality. Furthermore, the driving mechanisms differ substantially across population change units. In shrinking units, the effects of individual factors are generally stronger, with urban vitality showing greater dependence on key determinants. In contrast, growth units exhibit a more balanced contribution of factors and a more diversified driving structure. These findings reveal the differentiated roles of the built environment in shaping urban vitality in shrinking cities and provide empirical evidence for urban spatial governance under population shrinkage.