Which generation should migration promotion measures target to shortly achieve a compact structure for shrinking cities?

Abstract

Streamlining urban areas to appropriate sizes based on the current population structure is an important and urgent issue. Therefore, Japan enacted the Location Normalization Plan in 2014, and a shift toward a more compact regional structure is underway. However, this plan cannot force people to migrate to the target area. Consequently, the formation of a compact regional structure is expected to persist for several decades. It consequently is crucial to shortly convert to a compact regional structure based on the voluntary migration of residents before the living environment outside residential zones deteriorates. This study analyzed the time required for the population to reach zero in urbanization-promoting areas excluded from residential attraction, using spatial statistical analysis. We assumed that multiple generations were the targets of the migration promotion policy, and considered the differences in each scenario. The results demonstrate that >100 years would be required before the natural withdrawal of target areas, and that migration policies targeting pre- and post-retirement generations were the most effective. This paper's contribution is valuable in that it discusses the importance of promoting relocation based on the viewpoint of the shortest possible shrinkage to the compacting measures currently being undertaken worldwide in matured cities.