最优城市规模与特大城市户籍管制的自增强机制

Optimal city size and self-enhancement mechanism of Hukou regulation in megacities

人口500万以上的特大城市为了缓解其综合承载压力,倾向于通过严格的户籍管制政策控制人口规模,但在现实中,特大城市却存在着"落户越来越严、人口越控越多"的现象。基于最优城市规模理论,提出了特大城市户籍管制的自增强机制,并分析了其形成过程。研究发现,严格的户籍管制政策在降低特大城市排他性公共品拥挤成本的同时,并未改变城市人口增长带来的规模收益,这使得城市边际规模收益和边际拥挤成本相等时的最优规模理论值增大,城市人口倾向于进一步增多,最终导致户籍管制更加严格。利用286个地级市的数据对户籍管制的自增强机制进行实证分析发现:加强户籍管制不利于中小城市收入提高,有利于大城市和特大城市收入提高,人口规模越大的城市越具有加强户籍管制的倾向;户籍管制程度的提高使城市人均收入与人口规模之间倒U型曲线的顶点位置右移,因而提升了特大城市的最优人口规模水平,进一步促进了人口的流入。大多数特大城市在严格的户籍管制下,其实际人口规模仍未达到最优人口规模理论值,依然存在人口进一步增多的倾向。户籍管制的自增强机制的政策含义是:当前,中国的特大城市已经陷入了户籍管制增强与城市人口增多的恶性循环之中,通过严格的户籍管制控制城市人口规模的政策是无效的,进一步放开落户限制反而是特大城市疏解人口的有效途径;同时,应通过提高中小城市非排他性公共品供给水平引导新增非户籍人口有序转移,最终使特大城市退出户籍管制的自增强机制。

Strict Hukou regulation is often taken by megacities with over 5 million inhabitants to relieve its bearing pressure and control its size.While the truth is,the stricter household registration controlled,the more population it has.Based on the theory of optimal city size,this paper established a self-enhancement mechanism of Hukou Regulation in megacities and made a systematic analysis of its formation.It is found that though strict Hukou regulation has reduced the congestion cost of exclusive public goods,it does not influence the returns to scale of population growth,which gives rise to an increasing optimal city size obtained when marginal return of urban scale equals marginal congestion cost,a further expansion trend of urban population and ultimately a stricter Hukou regulation.The empirical analysis of the self-enhancement mechanism in 286 prefecture cities demonstrates that reinforced Hukou regulation nourishes big cities and megacities while undernourishes middle-sized and small cities,and thus the large-sized cities are more inclined to tighten its household registration policies.In addition,the reinforced Hukou regulation makes the inverted‘U＇curve vertex between urban per capita income and population size shift to the right,elevates m optimal population size in egacities and further promotes the inflow of population.The self-enhancement mechanism has challenged the Hukou policy in megacities.Under the condition of intensive Hukou regulation,most megacities do not reach its optimal population size and tend to increase its population.Being caught in the vicious circle between strengthened Hukou regulation and expanding population,megacities have failed to control its population size by strict Hukou regulation.To get rid of the self-enhancement mechanism,it is advisable to lift household registration restriction and improve the non-exclusive public goods in middle-sized and small cities to absorb non-registered transferred households.