An Empirical Study on Agglomeration Economies of Cities in view of Local Public Finance-A Basic Study for the Merger of Municipalities-

这个项目的目的是(1)根据日本所有城市的数据，研究城市规模与年度支出/收入的一般关系，(2)从地方公共财政的角度展示城市集聚经济的证据和城市的最佳规模，(3)定量估计城市合并对地方公共财政的影响。通过三年的研究，我可以达到上述目的，发表了许多论文和一本书。主要结果如下：(1)人均年度支出(对数变换)可表示为人口规模的二次凹函数(对数变换)。(2)独立于国家政府的人均收入(对数变换)可表示为人口规模的立方递增函数(对数变换)。人均收入(对数变换)依赖于国家政府，可以用二次凹函数来表示。(3)人口少于30万的城市存在规模经济，较大的城市存在规模不经济。(4)从地方公共财政的角度来看，一个城市的最优规模是200~30万人口。(5)通过这些结果，更大的市政协作区(341个区域)的合并将每年减少3.7万亿日元(约13%)的支出，相当于从东京到冈山县的高速公路建设成本。

The aims of this project are (1) to investigate the general relationship between the city size and the annual expenditure/revenue in the basis of data of all municipalities in Japan, througla this, (2) to show the evidence of agglomeration economies and the optimum size of a city in view of local public finance, and (3) to estimate quantitatively the effects of merger of municipalities on the local public finance.Trough this study for three years, I could achieve aims mentioned just above and publish many papers and a book, which were quoted at the discussion in academic associations and local governments.The main results are follows.(1) The per capita annual expenditures (logarithmic transformation) can be expressed at the quadratic, concave function of the population size (logarithmic transformation).(2) The per capita revenue (logarithmic transformation) which is independent from the national government can be expressed at the cubic, increasing function of the population size (logarithmic transformation). The per capita revenue (logarithmic transformation) which is dependent of the national government can be expressed at the quadratic, concave function.(3) We can find the economies of scale in cities which have less than 300 thousand of population, diseconomies of scale in lager cities. In towns and villages, we can find always the economies of scale.(4) The optimum size of a city in view of local public finance is about 20O〜300 thousand of population.(5) Through these results, the mergers of the Larger Areas for Municipal Cooperation which amount to 341 areas will reduce annual expenditures by 3700 bilion yen (about 13%) that is equal to the construction cost of high way from Tokyo to Okayama prefecture.