  China's demographic changes have important global economic and geopolitical
implications. Yet, our understanding of such transitions at the micro-spatial
scale remains limited due to spatial inconsistency of the census data caused by
administrative boundary adjustments. To fill this gap, we manually collected
and built a population census panel from 2010 to 2020 at both the county and
prefectural-city levels. We show that the massive internal migration drives
China's increasing population concentration and regional disparity, resulting
in severe population aging in shrinking cities and increasing gender imbalance
in growing cities.
