The effects of National High-tech Industrial Development Zones on economic development and environmental pollution in China during 2003-2018.

Utilizing National High-tech Industrial Development Zones (NHIDZs) as a quasi-natural experiment, this study has adopted 285 prefecture and above cities from 2003 to 2018 in China as the research samples and constructed the difference-in-differences (DID) and spatial difference-in-differences (SDID) models to investigate the effects of NHIDZs on economic development and environmental pollution at national, regional, and administrative levels. The results show that NHIDZs have basically achieved a win-win situation in promoting economic development and reducing environmental pollution at the national level. However, spatial heterogeneity is supported at regional and administrative levels. Specifically, "the law of diminishing marginal effect" of NHIDZs is proved in the eastern cities and key cities, which reveals the uneven development pattern of government leading in China, and highlights the importance and necessary of making policy according to local conditions and governing environmental pollution by classification.