There have been heated debates over the extent, causal mechanisms, and consequences of regional inequality in China and the proper policy intervention. The central government considers struggling poorer regions and the widening coastal-interior gap as serious threats to China's prosperity, stability, and unity, and has launched the Great Western Development Strategy. Given the massive scale of the region and its tremendous diversity, more work is needed on regional development in interior China and on how effective the Chinese government has been in developing its western region. This paper broadens the study of regional inequality in provincial China by focusing on the poorer western provinces through a case study of Gansu Province. We examine the extent and process of regional development in Gansu and its Hexi Corridor, and investigate the geographical and structural challenges facing a western province. We have found that despite the government's western development policies, huge gaps exist within interior provinces, and intra-provincial inequality and geographical concentration are rising continuously. While acknowledging the efforts and achievements of the government in reducing poverty and promoting the development of the west, we argue that the geography and structural problems of the interior provinces have seriously limited the effectiveness of government policy. The development of poorer regions in China remains a challenging task.