High-Speed Rail Opening, Economic Agglomeration, and Urban Innovation

The development of HSR (HSR) promotes the flow of economy and population, which can, to some extent, impact the innovation level of cities connected by it. This paper, based on city data from 276 prefecture-level cities and above from 2003 to 2016, employs the DID method and a mediation effect model to empirically analyze the relationship between the opening of HSR, economic agglomeration, and the level of urban innovation. The study finds that the introduction of HSR not only elevates the innovation level of connected cities but also manifests a mediation effect of economic agglomeration. Further research reveals that this mediation effect varies regionally and by city hierarchy. Specifically, in eastern regions, the mediation effect of HSR promoting urban innovation through economic agglomeration is less pronounced than in western regions. For central cities, the mediation effect is represented through economic density, while for non-central cities, it manifests through economic density, population density, and industrial density. Robustness checks further validate these findings, reaffirming the conclusions of this paper. Thus, the study’s findings offer policy insights, suggesting that local governments can leverage the economic agglomeration advantages brought by HSR and adopt differentiated and rational policy measures to promote high-quality urban development.