How Does High-Speed Rail Promote Green Innovation in China: Empirical Analysis Based on Panel Data of 284 Cities

Utilizing the panel data of 284 cities from 2005 to 2019 in China, this paper employs the multi-period difference-in-differences model to explore the impacts of the opening of high-speed rail (HSR) on green innovation as well as the underlying mechanisms and heterogeneity in the impacts. The results show that the opening of HSR effectively promotes green innovation, and this finding remains robust after a series of robustness tests. The positive impact operates not only by fostering labor agglomeration and increasing R&D expenditure but also by stimulating demand for green technologies through talent concentration and tourism expansion. Heterogeneity analyses show that the effect is concentrated in peripheral cities, cities with weaker innovation endowments, and smaller-scale cities. Based on further classification of green patent records show the opening of HSR actively promotes the growth of substantive green innovation and green innovation by enterprises, and exerts a stronger effect on green innovation in heavily polluting industries. We further demonstrate that HSR opening significantly promotes inter-city collaborative green innovation. Our findings shed new light on the economic and environmental effects of improvement in transportation infrastructure.