Is port integration a panacea for regions green development: An empirical study of China port city

Port integration (PI) can eradicate homogeneity and disorderly competition, realize the green intensive development of port cities, and is a crucial step in enhancing port competitiveness. This paper builds an assessment framework for green development efficiency (GDE) that takes social welfare, environmental regulation, economic growth into account, and uses the Super-SBM model to calculate the GDE based on panel data from 113 Chinese port cities from 2003 to 2020. Furthermore, the influence of PI on the GDE of port cities and its transmission mechanism is assessed using the PSM-DID model. The results show that the GDE of port cities has a fluctuating upward trend, but the overall level is low, and the social development index (SDI) can effectively improve the efficiency level. PI can significantly improve the urban GDE, and various robust results show that the above conclusions are credible. Heterogeneity analysis reveals that PI contributes more to the GDE of inland port cities than it does to coastal port cities. The GDE of the small-medium sized cities can be greatly enhanced by PI, and the results are better when the "Government driven + market decided" pattern is used. PI encourages technology innovation, which can enhance the urban GDE. Finally, some policy recommendations are made to encourage the excellent development of Chinese port cities.