Variation of Population Distribution between Daytime and Night-time in Japanese Cities

Abstract

The daily movement of population or commuting is a common phenomenon in a modern city. This phenomenon brings the variation of population distribution between daytime and night-time, which can be indicated by the ratio of daytime population to night-time or residential population calculated on the basis of place-of-work and place-of-schooling data.Observing the maps presenting the ratios of daytime to night-time population by shi, ku, machi, and mura (minor administrative divisions) based on the 1970 population census results, it is recognized in general that the city with the ratio of 100.0 and over or larger population in daytime than in night-time is surrounded by the minor administrative divisions with the ratio of less than 100.0 or smaller population in daytime than in night-time, and it may be suggested that the former is greater in the centrality than the latters.The changes in the ratio of daytime to nighttime population over 1960 to 1970 for all of the cities present that in general the ratio increased in the city with that of 100.0 and over for 1960 while it declined in the city with that of less than 100.0 for 1960 over the period from 1960 to 1970. Accordingly, it may be implied that the centrality in the former city has become greater while that in the latter city has been smaller in 1970 than in 1960.In Tokyo and Osaka cities the population density in daytime by each ward as of 1970 presented the highest at the city center; and the further the distance from the center, the lower the density. On the other hand the density in night-time indicated the highest at the inner zone located outside the city center and it showed rather low at the city center.Examining the population densities in both daytime and night-time by wards of Tokyo for 1930, 1940, 1947, 1960, 1965, and 1970, it was found that the pattern of change of population densities in both daytime and night-time over the period from 1930 to 1970 was different by location of ward. Based on the difference of the pattern twenty three wards were classified into the following five types: the city center type, the inner zone type, the sub-center type, the outer zone type, and the suburban area type. Also, it was found that the area showing the highest population density in daytime was Taito-ku, the traditional commercial district, in 1930 and 1940, but it shifted in 1947 to Chuo-ku, the commercial and business district, and then it moved to Chiyoda-ku, the modern central business district, in 1960. Similar process was recognized in Osaka city.