Municipal Mergers and the Change in Intra-Prefectural Migration

1. Purpose of the study Since 1995, the national government has repeatedly revised the Special Municipal Merger Law (so called (Kyu) Gappei Tokurei Ho). These revisions are aimed at promoting the consolidation of municipalities so that these municipalities could effectively cope with various local and regional issues, such as their financial crises and ongoing population aging (e.g. Sasaki 2004, Ministry of Internal Affairs and Communications 2006). In response to the changes in that law, a large number of municipalities have stepped into the process of merging with neighboring municipalities, and as a result, the total number of municipalities in Japan has sharply declined. This process of large-scale municipal mergers has often been called "Heisei no Daigappei" (the Great Heisei Merger), the third of its kind in the modern history of Japan, following those undertaken in the Meiji and Showa periods. In the course of the "Heisei no Daigappei," the level of intra-prefectural inter-municipal migration has gradually declined. This seems largely to be caused by the fact that some portions of intermunicipal migration have turned into intra-municipal moves due to the mergers of municipalities and have formally disappeared from counts in the migration statistics. At the same time, we might a lso observe that local socio-economic transformations stimulated by municipal mergers,1 as well as various other factors unrelated to mergers, changed the level of migration. Presently, however, we cannot clearly articulate the causes of migration changes, because it may take some years to verify the extent to which the socioeconomic impacts of mergers actually influence the level of migration.2 For the analysis of recent change in intra-prefectural inter-municipal migration, our primary task for the time being would thus be to grasp the trend in intra-prefectural inter-municipal migration and provide basic information on its characteristics in relation to municipal mergers. The purpose of this paper is to describe the recent trends in intra-prefectural inter-municipal migration (henceforth denoted simply as intraprefectural migration) and the change in the number of municipalities during the time of the "Heisei no Daigappei." Since the vast majority of mergers have been completed by the end of March 2006, this paper observes the trend up to April 2006, the month right after the "Heisei no Daigappei." Generally speaking, an in-depth analysis of intraprefectural migration requires inter-municipal OD (origin-destination) migration data. Such data, however, do not exist for some prefectures. The only statistics of intra-prefectural migration which cover all prefectures are the total number of intraprefectural migration for each prefecture compiled from the Basic Resident Registers. In this paper, we use these data and information on municipal mergers provided by the Ministry of Internal Affairs and Communication (2006) and reveal the general relationships between the municipal mergers and the change in intra-prefectural migration. Then we supplement these findings by the analysis of OD data of selected prefectures. In the next section, we firstly show the overall changes in the numbers of municipalities and intraprefectural migration. Section 3 then describes their changes at the prefecture level. Section 4 Abstract The purpose of this paper is to describe the recent changes in the number of municipalities and intraprefectural inter-municipal migration (abbreviated as intra-prefectural migration). During the time of "Heisei no Daigappei," the number of municipalities notably decreased. But the decline in intra-prefectural migration was relatively small. At the prefecture level, the change in intra-prefectural migration relative to that of the number of municipalities shows a negative correlation with the average number of merged municipalities per merger, and a positive correlation with the average population of town/village municipalities. This paper also examines the situations of Niigata and Okayama prefectures, where the changes in the numbers of municipalities were similar but the levels of decline in intra-prefectural migration differed. Our analysis suggests that the larger average population of town/village municipalities in Niigata and relatively weak migration connection among the merged municipalities in Okayama would partly explain the larger relative change in intra-prefectural migration in Niigata. The Japanese Journal of Population, Vol.5, No.1 (March 2007)