Age structural characteristics of population shrinkage at the county level from 2000 to 2020 and the future predictions in China

In recent years, regional population decline in China has received widespread attention, yet few studies have analyzed the age structural characteristics of population shrinkage. Utilizing data from the fifth, sixth, and seventh population censuses, this study categorizes different age groups into children, youth, middle-aged, and elderly, and summarizes several types of population shrinkage: complete shrinkage, shrinkage except for the elderly, youth-driven shrinkage, middle-age collapse, and wave-like shrinkage. It analyzes the causes of population shrinkage across age groups from two perspectives of demographic structure and migration. Finally, it predicts the age structural types of population shrinkage regions from 2020 to 2030. The main findings are as follows: (1) Youth-driven shrinkage was the dominant type from 2000 to 2010, accounting for over 50% of all samples, with a concentration in the northeast region, coastal areas, and Southwest China. Wave-like shrinkage also accounted for a significant proportion, mainly in Northwest China and the Sichuan-Chongqing region. (2) From 2010 to 2020, youth-driven shrinkage remained the most prevalent type but gradually shifted towards the type of shrinkage except for the elderly, particularly in the northeast region. Moreover, wave-like shrinkage has mainly transformed into the types of youth-driven shrinkage and shrinkage except for the elderly. (3) Age structural factors are becoming the primary reason for the decline in young population in shrinking regions, while the decrease in population aged 35-64 is primarily influenced by population migration. (4) Under the current fertility scenario, it is predicted that over 80% of regions will experience population shrinkage from 2020 to 2030, with shrinkage except for the elderly emerging as the dominant type. This study provides a new perspective for a more comprehensive understanding of population shrinkage and supplies supports for formulating strategies to address population shrinkage in China.