New evidence of high-speed rail promoting green economic growth in the Yangtze River Economic Belt: empirical analysis based on difference-in-differences

The Yangtze River Economic Belt (YREB) is an important ecological barrier in China. From new perspectives, this paper explores the mechanism of high-speed rail (HSR) for green economic growth (GEG) in the YREB. This paper constructs 108 city panel data at the prefecture level and above in the YREB from 2003 to 2020. Difference-in-differences (DID) is adopted to research the impact of high-speed rail on GEG in the YREB. (1) HSR has significantly improved the GEG of the YREB. The effect value is 4.88%. The parallel trend test suggests that DID is valid. A time-varying instrumental variable combining average altitude and historical railway network is constructed for the endogeneity test. (2) Propensity score matching (PSM) and DID (PSM-DID) were employed to test the sample selection bias. (3) A battery of robustness tests, including the placebo test, variable replacement, and policy interference exclusion, is carried out. The conclusions are still valid. (4) HSR can promote the GEG of the YREB by encouraging technological innovation, industrial upgrading, and increasing ecological efficiency. The contribution rate from the largest to the smallest is ecological efficiency, industrial upgrading, and technological innovation. (5) Heterogeneity analysis shows that HSR has played an important role in encouraging GEG in the eastern, peripheral cities, and the downstream cities of the YREB. Finally, this paper puts forward policy suggestions for promoting GEG in the YREB.