A Cohort Analysis of Internal Migration in Japan during the 1940s

Abstract

This study clarifies trends and factors in internal migration of Japan in the 1940s, including during World War II and the postwar reconstruction period, through cohort analysis using the total results of population by age in population surveys from 1944 to 1946 and the extraordinary national census in 1947. The results are described below. First nationwide cohort changes from 1944 to 1947 were examined. The results revealed that each cohort of males changed dramatically due to military service, war deaths, and military demobilization, while changes in female cohorts were relatively small. Next, prefectures were classified by cluster analysis based on the population ratio by single-year age in 1944. The results showed that the young male labor force in rural regions concentrated into urban areas, and the tendency was affected by the development of military industries. From 1944 to 1945 with the end of the war, much of the population migrated from large cities and military industry areas to rural areas because of evacuations. The evacuations were not conducted systematically, except for student group evacuations, and people relied on relatives and connections based on recommendations in choosing evacuation sites. As a result of back-flow evacuation relying on relatives and connections, many people evacuated to areas from which large numbers of the population had migrated to Tokyo and Osaka Migration due to evacuation was seen in all age-groups, which is a major difference compared with the usual population migration pattern. Both domestic migration and military service affected population migration among men, and the labor force drastically decreased in new military industry areas. Finally, the processes of population recovery in large cities after 1945 were examined. It was found that the population in Tokyo and Osaka had recovered to that in around 1940 by 1955, but the population was approximately 60% of that in 1940 when the population in relation to the various cohorts was compared. Hence, births and the inflow of new cohorts played a major role in population recovery in Tokyo and Osaka after the war. The reason why the cohort size did not recover in large cities was probably due to factors such as food shortages, delays in reconstruction, and the control of population inflow to urban areas. In addition, new male successors were necessary in rural areas due to the large number of war deaths.