A review of the research on externality of urban network

Urban network research has become the frontier academic field of international urban research and has gradually become a hot spot. At present, the related literature on “urban network” mostly focuses on conceptual discussion, dimension analysis, and network structure analysis. Research on the influence of network on regional economic development is relatively weak. Externality, as an essential attribute of urban network, is of great significance to the evolution of urban network and the development of cities and regions. This article starts from a comparison of agglomeration externalities with urban network externalities, focusing on the review and evaluation of the formation mechanism, utility, and measurement methods of urban network externalities.The synergy effect, integration effect, and borrowing size are considered important reasons for the formation of urban network externalities. The research on the effectiveness of urban network externalities focuses on two aspects. The first is the role of factor mobility in promoting knowledge diffusion and innovation, and the second is the impact of urban network on competitiveness and economic growth. Based on the existing literatures, the research on the measurement of urban network externalities mainly involves identification and estimation, including three common methods as correlation analysis, regression analysis, and spatial econometric analysis. The existing empirical researches on externalities are still mostly based on static analysis and lack dynamic consideration. The issues that need further attention in the future include theoretical understanding of urban network externalities, externality measurement methods, and empirical research.