中国城市人口密度过高了吗:经济增长的视角

优化人口分布空间格局、提高城镇化质量对未来保持经济增长的重要性不言而喻,但对于如何优化人口分布格局和提高城镇化质量,现有的文献存在持续争议。文章从经济发展的过程来讨论城市最优人口密度问题,认为各城市之间存在一种赶超现象,少数城市是吸收和转化国外技术的主要场所,是本国的增长前沿,其他城市通过接受前沿城市的溢出来实现增长,城市人口的最优密度与城市在宏观经济增长中的角色有关,人口密度对经济增长的影响随城市在经济发展中的作用不同而不同。借鉴发展经济学的理论,文章在一个赶超的框架下分析了人口密度对城市经济增长的影响,重点考察在靠近增长前沿和远离增长前沿的城市中人口密度对经济增长的影响是否存在差异。运用1999—2014年中国地级以上的城市数据,实证结果表明,对于靠近增长前沿的城市来说,人口密度的经济增长正效应更大;对于远离增长前沿的城市来说,人口密度的经济增长正效应更小或效应为负;进一步研究发现,城市人口密度对经济增长的这种非线性效应随着与增长前沿城市的空间距离和行政边界数量增加而衰减。文章结果意味着,限制增长前沿城市的人口密度将会对它们的经济增长产生负向影响。下一步城镇化的政策重点应该是对这些城市做好发展规划,在增加城市人口密度的同时,通过科学规划公共服务设施和交通基础设施的空间分布,从而控制这些城市的拥挤,而不是简单地限制人口进入和将人口分布在广阔的空间上。

Is China's Urban Population Density Too High: A Perspective of Economic Growth

The importance of optimizing the spatial pattern of population distribution and improving the quality of urbanization for maintaining economic growth in the future is self-evident, but there are persistent disputes about how to implement them in the existing literature.This paper discuss the problem of optimal population density of cities from the process of economic development, and think that there is a catch-up phenomenon among cities, a few cities are main places to absorb and transform foreign technology, they are growth frontiers of their own countries, other cities achieve growth by accepting the spillover of frontier cities, and the optimal population density of cities is related to the role of cities in macroeconomic growth.The impact of population density on economic growth varies with the role of cities in economic development.Using the theory of development economics, this paper analyzes the impact of population density on urban economic growth under a catch-up framework, focusing on whether there are differences in the impact of population density on economic growth between cities near and far from the growth frontier.Using the data of China's cities above prefecture level from 1999 to 2014, and taking the order of urban population size as instrumental variable of population density, the empirical results show that when we control other factors, the effect of urban population density on economic growth is nonlinear, and the positive effect of population density is greater for cities near frontier of growth;For cities far from the frontier of growth, the positive effect is smaller or even negative;Further results shows that the nonlinear effect of urban population density on economic growth decreases with the spatial distance and administrative boundaries to growth frontier cities.The results of this paper imply that restricting the population density of frontier cities will have a negative impact on their economic growth.The next step of urbanization policy should focus on the development planning of these cities,while increasing urban population density, through scientific planning of public service implementation and spatial distribution of transportation infrastructure, so as to control the congestion effect of these cities, rather than simply restricting population entry and distributing population in a broad space.