Regional Population Ageing in South Korea: Assessing the Impact of Internal Migration 2012–2023

Abstract South Korea is experiencing rapid population ageing, with pronounced differences between rural and urban areas. Internal migration, which plays an important role in South Korean society, may contribute to these regional disparities. This study examines the contribution of internal migration to regional age-structure changes in South Korea between 2012 and 2023. Using administrative data from 17 provinces and 229 municipal units, distinguished by their degree of urbanization, we perform a decomposition analysis to assess the impact of internal migration on regional old-age dependency ratios. The results reveal substantial differences in internal migration patterns and their effects on regional age structures. Notably, internal migration has decelerated population ageing in the provinces of Jeju, Sejong, and Seoul, while accelerating it in most other provinces. At the municipal level, towns and semi-dense areas have benefited the most, reflecting evolving suburbanization processes as well as the influence of large-scale spatial development policies. While the overall impact of internal migration on population ageing is moderate, it has reduced disparities in old-age dependency ratios between highly and moderately densely populated areas. In contrast, the faster population ageing in rural areas can be partially attributed to internal migration. Beyond migration among young and middle-aged adults, migration at older ages also plays a meaningful role in shaping these dynamics. Overall, the findings highlight the importance of considering internal migration when analyzing regional disparities in ageing societies.