This paper quantifies and compares the influence of two modes of transport on tourism, namely, high-speed rail (HSR) and air travel, and explores their substitute or complementary relationships. To facilitate the analysis, we apply data from 291 prefectural administrative cities in China from 2003 to 2019. Empirical tests show that both modes have a significant positive influence on the development of tourism. Moreover, the effect of air travel is greater than that of HSR. The findings remain robust and reliable with changes in the explanatory variables and sample size, and with regard to time window adjustment and endogeneity. Further, we explore the differences in the strength of the influences and find the two modes exhibit various effects according to regional heterogeneity. Finally, we investigate the joint effect of the two modes and find the existence of a substitute relationship. However, the relationship changes to complementary in specific areas. The findings of this paper provide important implications for the development of the regional tourism economy and the spatial layout of the transport infrastructure.

The resilience of the fiscal system has a driving effect on environmental governance, and it is always a challenge to solve the problem of matching fiscal power with administrative power. Based on the panel data of 193 cities in China from 2013 to 2018, the data envelopment analysis method was used to evaluate the comprehensive indicators of urban environmental efficiency. The impact of fiscal stress on environmental efficiency is examined from the perspective of urban horizontal imbalance. We find that the smaller the fiscal stress, the higher urban environmental efficiency. The endogeneity is mitigated by using instrumental variables and the generalized method of moments, and the results are still robust after considering the interference of sample selection bias and variable estimation bias. At the same time, the impact of fiscal stress on environmental efficiency varies with spatial location, ecological strategic planning, economic development, and other factors, especially in southern cities, cities in the Yangtze River Basin, and cities in urban agglomerations, where reducing fiscal stress promotes environmental efficiency. In addition, green production and public environmental services are important channels for its role, and the rational allocation of self-raised funds can effectively moderate the improvement of environmental efficiency.

The COVID-19 epidemic in China has been effectively controlled. It is of great significance to study the law of cross-regional spread of the epidemic, for the prevention and control of the COVID-19 in the future in China and other countries or regions. In this study, the cross-regional connection intensity between cities was characterized based on the probability and the effective distance of the shortest path tree, and the empirical analysis was carried out based on the high-frequency data such as the cases of COVID 19 outbreaks. It is concluded that the higher the intensity of inter-city connection, the larger scale the cross-regional spread of the epidemic.

Hu line is the dividing line of Chinese population density, geography, culture, and economy. The areas on both sides of the Hu line are in completely different stages of development, and have development modes. Based on the 3D research framework, and using the panel data of 335 cities in China from 2000 to 2013, our study examines the driving factors and the influence mechanism of productivity in the cities on both sides of the HU line. We find that economic growth in low-density areas depends more on increased density and division, while economic growth in high-density areas depends more on decreases in distance and segmentation. In addition, the mechanism test illustrates the heterogeneous growth mechanism on both sides of the HU line. The cultural diversity in low-density areas promotes economic growth by promoting diversified economy; while the cultural identity in high-density areas promotes specialized economy and thus promotes economic growth. Our study provides new empirical evidence for the informal institutional reasons behind the economic development, and also provides a useful reference for the economic development of the multi-ethnic areas in China.