The Japanese Urban System Based on the Analysis of Internal Migration

Abstract

It is important for the study of an urban system to clarify the functional characteristics of each city as an element of the urban system and to analyse the interrelations among the cities. However, the studies of the latter have not been undertaken till now because of difficulties in data collection. Fortunately, migration data for each city during the one year after October 1979 were published in Vol. 6 of the 1980 Population Census of Japan. Using this the writer atempts to make clear the characteristics of interrelations in the Japanese urban system. The results are summarized as follows:1. The Japanese urban system presents a typical hierarchical structure as seen in Christaller's model. Differing from Pred's model of innovation diffusion, the migration flows between cities of the same order or between larger and smaller cities, independent of tributary areas, are large on neither volume nor proportion. As shown in Fig. 3, Osaka follows Tokyo, the national centre. Then come Sapporo, Fukuoka, Sendai and Hiroshima, regional urban centres. Viewed functionally and structurally, Nagoya also is included in this group. Following it appear central cities, mostly consisting of prefectural centres, that get nodal flows of over 10 percent from some cities of smaller scale within their own prefecture. Yokohama, Kyoto and Kobe, in the Tokyo and Osaka metropolitan areas respectively, are considered as satellite centres; they do not attain the level of functional allotments in each metropolitan area.2. As seen in Fig. 1, the metropolitan dominance of Tokyo has expanded remarkably. Not only Ibaragi, Tochigi and Gumma prefectures in the northern Kanto district, but also Fukushima in Tohoku, and Yamanashi and Nagano in the Chubu district are included in its area. It seems that in these prefectures the prefectural centres, occasionally in conjunction with the second largest cities, had once formed their own local urban systems.3. By the analysis of social increase of the urban population and the net migration ratio of nodal flows for each city, three types of cities are recognized (B, C and D types as shown in Fig. 4). Most of the smaller cities with less than 100, 000 inhabitants show a social decrease and net out-migration to central cities so that they continue to decline as before. Although the return migrations to native town or to neighbouring larger cities has normally been recognized since Japan's high economic growth period (about 1960 to 1973), these phenomena account for only a part of out-migrants. On the other hand, central cities and regional urban centres show social increase in spite of the net out-migration of nodal flows to metropolitan centres. Accordingly, we can see that such central cities and regional urban centres play a role in absorbing the population from surrounding areas and losing their own population to metropolitan centres. Within the metropolitan areas, satellite towns continue to increase in population, not only from natural increase of their own population but also from the net in-migration from the metropolitan centres. Therefore, as long as such migration flows continue, the hierarchical structure of the national urban system will continue to be developed and at the same time the regional disparity between metropolitan and non-metropolitan areas will continue to expand in contrast with Western countries.4. The metropolitan areas such as Tokyo, Osaka and Nagoya continue to dominate a hierarchical structure. Intermetropolitan migration between them has not been developed until now. Because of the dominance of nodal flows, the second or third largest flows, such as the inter-metropolitan migration between Osaka and Nagoya, are not so great in volume. Without structural changes in the urban system, we cannot say that the Tokaido Megalopolis is completely formed.