[Figure 4]
Regional urbanization levels also differed spatially and temporally (Table S1, Fig 5). The northwest and southwest regions behaved the lowest population urbanization level. All regions increased over time, with the differences among them gradually decreasing (Fig 5a). Economic urbanization level was the highest in the east and north, followed by the central and south, and the lowest in the northwest (Fig 5b). In terms of spatial urbanization, the central and eastern regions behaved higher values. The regional values varied significantly in different periods (Fig 5c). For instance, the spatial urbanization level in northeast China was low in 2000~2005 and high in 2010~2020, while the opposite was observed in the Northwest region, which reached its peak in 2000. Although there were differences in the regional social urbanization level, the inter-annual variations were not obvious (Fig 5d). In terms of social urbanization values, the eastern region behaved the highest, all above 0.02, while the northwestern region presented the lowest. In addition, the comprehensive urbanization levels of the seven regions from high to low were: east, north, central, south, northeast, southwest, and northwest. Among them, the east and southwest increased dramatically, while the northeast decreased evidently (Fig 5e).