The post office network has been developing in Japan since 1871. In the formation of this network, the post office has contributed to the formation of modern spatial organization in Japan. In order to explain this geographical situation concretely, the distribution of this communication facility during different development periods is compared with the growth of central places and the distribution of other public facilities, and so the hierarchical linkages in the postal system are presented as one example of a modern integrated system formed by rational interregional relations. This paper discusses these points based on a case study of Hiroshima Prefecture.
The results obtained are as follows:
(1) The history of the post office network can be divided into three phases (1871-1900; 1900-1945; 1945-), according to features of its growth.
a) Before 1882, the post office network was developed in many places at the same time. This sudden expansion was caused by historical and political conditions in the Meiji era and the introduction of post office management by contractors. After 1882, a number of post offices were closed because of the contractors' financial difficulties. During the Meiji era, post offices developed in central places belonging to higher class than the lower order central places where primary schools and/or village offices were located.
b) In the second phase (1900-1945) the post office network became denser. A number of non-collection-delivery post offices were concentrated in densely populated urban areas. On the other hand 70% of the settlements in rural areas having a town office or village office got post offices. The allocation of collection-delivery offices was nearly completed during this phase. The reformation of postal districts was carried out in order to bring them into conformity with administrative districts and the homogeneity of each area.
c) The reopening of closed post offices in war-damaged cities (e. g. Hiroshima) characterized the locational development of these facilities in the postwar period. However the basic locational development pattern did not change. In urban areas the distribution of post offices has become denser in city centers and then expanded to suburban areas. Today most of the lower order central places in rural areas have also received post offices. Depopulation in rural mountainous areas has caused some closures of post offices in recent years. These closures will probably have an important effect on the locational development of post offices in the near future.
(2) The hierarchical linkage among post offices is made clear by analyzing the internal organization of postal services. As indicators of this system, the grade of post offices, mail routes, the flow of funds used in post offices, and some designated post office were selected. As a result, it was found that the hierarchical linkage, which included the Hiroshima office as a first order center, and Kure, Fukuyama, Onomichi and Miyoshi offices as second order centers, has been formed and tightened in relation to modernization of the central place system. Especially, the centrality of the Fukuyama and Miyoshi offices has increased in recent years. Additionally, since the 1930's third order centers have began to appear, for example Mihara, Takehara, and Shobara offices. They have been established in central places reorganized as municipalities since the 1930's and had their status raised to ordinary post offices in the 1940's.
Two aspects of the post office -its locational development and its hierarchical integration-were dealt with. These two aspects of the post office indicate effects of national policy and the reformation of the regional system at the same time.
