Multi-dimensional population attractiveness and its characteristic changes of mega-city regions in China

Mega-city regions (MCRs) are the main spatial pattern of urbanization in China. Studying changes in the population attractiveness of these regions is significant for understanding their role in regional development and evaluating the effects of regional development policies. Using data on inter-prefecture migration from the 1‰ individual database of the national censuses conducted in 2010 and 2020, this paper analyzes the changes in population attractiveness within China's mega-city regions from three dimensions: intensity, range, and spatial evenness. The results show that: (1) In terms of intensity, the three major MCRs—the Yangtze River Delta, the Pearl River Delta, and the Beijing-Tianjin-Hebei region—are far more attractive than others. They altogether attracted over half of all inter-prefecture migrants in China. The attractiveness gap between MCRs in the east and those in the central and western regions narrowed from 2010 to 2020. Most eastern MCRs saw slow growth in their migrants, leading to a decline in their share of China's total number of migrants. The Yangtze River Delta experienced the most significant reduction. In contrast, central and western MCRs grew more rapidly in terms of migrants, becoming increasingly attractive. Notably, the Chengdu-Chongqing MCR and the middle reaches of the Yangtze River MCR experienced the fastest growth. In terms of attractiveness range, eastern MCRs mainly attract inter-provincial migrants, with the Shandong Peninsula MCR attracting population from a relatively small area. In contrast, central and western MCRs mainly attract intra-provincial migrants, although the Northern Slope of the Tianshan Mountains MCR is an exception, attracting inter-provincial migrants. Over the past ten years, there has been a noticeable trend of people moving shorter distances. Regarding the evenness of attractiveness within MCRs, most eastern MCRs exhibit a relatively even attractiveness among their cities. Notably, the evenness of the Yangtze River Delta and Pearl River Delta significantly increased from 2010 to 2020. However, the Beijing-Tianjin-Hebei and Central and Southern Liaoning MCRs show uneven attractiveness. In most central and western MCRs, the appeal is concentrated in core cities, although the spatial evenness of attractiveness has improved in the Chengdu-Chongqing, Beibu Gulf, and the Northern Slope of the Tianshan Mountains MCRs. (2) The three dimensions of population attractiveness are correlated. Compared to the MCRs in the central and western regions, those in the eastern region exhibit stronger attractiveness, mainly attract inter-provincial migrants, the attractiveness of each city is more evenly distributed, and the overall development of eastern MCRs is more advanced. However, as the MCRs in the central and western regions began to develop over the past decade, their population attractiveness did not fully evolve to match the characteristics of the eastern MCRs. The difference is that the proportion of inter-provincial migrants attracted by central and western MCRs has decreased, and these MCRs have consistently remained centers of population inflow within their respective provinces. (3) The multi-dimensional characteristics of population attractiveness change as the economic growth of MCRs progresses and as core cities develop and their functions spill over. Finally, based on the development goals of MCRs in different regions and the evolving characteristics of population attractiveness, we propose policy suggestions for the future development of MCRs.