Urban eco-efficiency and its influencing factors in Western China: Fresh evidence from Chinese cities based on the US-SBM.

• We analysed the influencing factors of urban eco-efficiency in Western China. • The US-SBM model and spatial econometric models were used for 84 cities' data. • Urban eco-efficiency showed a fluctuating upward trend during 2004–2017. • Economic development and urbanization had U-shaped impact on urban eco-efficiency. • Four explanatory variables showed a positive impact on urban eco-efficiency. Improving eco-efficiency can promote sustainable development. This study first evaluated the urban eco-efficiency of 84 cities in Western China from 2004 to 2017 by the undesirable-super-slack-based measure (US-SBM) and analysed their spatiotemporal characteristics, and then investigated its influencing factors using spatial econometric models. The results indicated that the urban eco-efficiency in Western China was at a relatively low level and showed a fluctuating upward trend with the highest average value of 0.65; however, capital cities of Western China have improved their eco-efficiency rapidly. Furthermore, there were obvious spatial spill-over impacts of the urban eco-efficiency in Western China. This paper also found that both the economic development level and urbanization level have "U" shaped impacts on Western China's urban eco-efficiency, which decreases at first and then rises. Similarly, increasing the proportion of secondary industry promotes urban eco-efficiency, and FDI, trade activities, improved environmental regulations as well as technological innovation capabilities have a positive impact on urban eco-efficiency in Western China. This paper also put forward corresponding policy suggestions to promote Western China's urban eco-efficiency. The present study may be helpful for policy-makers to balance economic development and environmental protection in Western China. [ABSTRACT FROM AUTHOR]