Resource-based cities (RBCs) face serious environmental pollution, and there are efforts to try to overcome those challenges by transforming industrial structure through investing in new technologies. Based on the panel data of 114 prefecture-level resource-based cities in China, this paper uses the difference-in-differences (DID) method to identify the effects of the “Broadband China” pilot policy on the carbon emission efficiency of resource-based cities. The results show that the “Broadband China” pilot policy has a significant effect on the improvement of carbon emission efficiency of resource-based cities, and the results are still valid after parallel trend test, PSM-DID estimation and placebo test. This study also finds that there are differences in the carbon emission efficiency of different locations and types of resource-based cities. In addition, the results of the mechanism analysis show that the “Broadband China” pilot policy can promote the improvement of carbon emission efficiency by promoting the upgrading of the industrial structure, the accumulation of human capital and the improvement of the level of urban innovation of resource-based cities. The findings provide a reference for China’s resource-based cities to develop the Broadband infrastructure, realize industrial upgrading, accumulate human capital and improve urban innovation level, and promote low-carbon transformation and improve carbon emission efficiency.

The environmental effects of national new areas have been an important topic but received little attention in academia. This study conducts a quasi-natural experiment using panel data of China’s 282 prefecture-level cities from 2006 to 2019, and evaluates the establishment of national new areas on urban ecological efficiency using the staggered difference-in-difference (DID) method, tests the robustness, and further examines the influential mechanism and urban heterogeneity of the empirical results. The results show that the establishment of national new areas has significantly improved urban eco-efficiency. Moreover, the mechanism analysis of the influences shows that national new areas improve urban eco-efficiency by improving urbanization level and urban transportation infrastructure. In addition, the heterogeneity analysis of cities shows that national new areas of cities in eastern and central regions are both significantly improving urban eco-efficiency, while those in western and northeastern regions are not. Furthermore, the promotion effect in the regions of “one new area in one city” model is better than that in “one new area in two cities” model; national new areas in non-resource-based cities show more positive effects on promoting urban eco-efficiency than those in resource-based cities. The conclusions reliably evaluate the results of the current construction of national new areas and provide feasible suggestions for further implementation of the related policy to balance economic development and environmental protection.