High-speed rail operations, the cross-regional mobility of highly skilled talent, and regional innovation—evidence from the Yangtze River delta in China

The correlation between high-speed rail (HSR) and regional innovation is vital for studying the economic impacts of HSR. Using 2003–2018 panel data on prefecture-level cities in China's Yangtze River Delta (YRD), this paper investigates the impact of HSR on regional innovation using a multiperiod difference-in-differences (DID) model. HSR operations have a significant positive impact on urban innovation, as supported by robustness tests. Heterogeneity analysis reveals a threshold effect of cognitive capital on the promoting effect of HSR on regional innovation that is maximized when cognitive capital capacity falls within the range of 0.1254 to 0.1876. Mechanism analysis suggests that HSR construction facilitates the cross-regional mobility of highly skilled individuals. This expanded movement increases innovation within cities due to the resulting knowledge spillovers. Moreover, HSR operations and civil aviation, as well as internet communication tools, play a significant complementary role in promoting regional innovation. This study deepens the understanding of the impact of HSR operations on regional innovation from the perspective of the interregional mobility of highly skilled people. Furthermore, ArcGIS is used to construct the 'least cost path' of the HSR network, providing a new approach to addressing the endogeneity of HSR station locations.