人口减少与区域的消失：应对之策
第二集：通过经济理论和数据解读日本城市过去50年的发展

The past half-century in Japan has been characterized by the comprehensive development of high-speed railways, expressways, air routes, and the widespread adoption of the internet and smartphones, resulting in a substantial decline in transportation and communication costs. Given that the agglomeration of people and firms in cities is fundamentally driven by the costs associated with mobility and communication, changes in the costs of moving people, goods, and information have exerted a significant influence on the spatial distribution of the population. This paper analyzes, through the framework of economic agglomeration theory, how the enhancement of transport and communication infrastructure—effectively dismantling distance barriers—has transformed inter- and intra-urban population distribution. Particular attention is paid to the underlying mechanisms driving these shifts, with a focus on cities as the focus of population agglomeration.