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

本项目的目的是：(1)基于日本所有直辖市的数据，研究城市规模与年度支出/收入之间的一般关系；(2)从地方公共财政的角度展示集聚经济和城市最优规模的证据；(3)定量估计城市合并对地方公共财政的影响。通过三年的学习，我达到了上面提到的目标，发表了多篇论文和一本书，在学术协会和地方政府的讨论中被引用。主要结果如下。(1)人均年支出（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）可以表示为人口规模的三次递增函数（对数变换）。依赖于国家政府的人均收入（对数变换）可以用二次凹函数表示。(3)人口在30万以下的城市存在规模经济效应，人口在30万以下的城市存在规模不经济效应。在城镇和乡村，我们总能找到规模经济。(4)从地方财政角度考虑，城市的最优规模约为20 ~ 30万人口。(5)通过以上结果，合并341个地区，每年可节省37000亿日元（约13%）的费用，相当于东京至冈山县高速公路的建设费用。

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.