Polycentricity or dispersal? The spatial transformation of metropolitan Shanghai

Debates of polycentricity or dispersal concerning the locational patterns of decentralized employment have caused widespread concern owing to their differing social and economic consequences. However, studies relating to these debates do not account for the reasons for the inconsistencies. Based on available point employment data, this paper seeks to respond to the debates by documenting and explaining the spatial transformation of Shanghai at different geographic scales. We find that the period from 2004 to 2008 captures a trend of employment centralization. But a reverse trend of decentralization occurred between 2008 and 2013, which is characterized by general dispersal at a large scale, accompanied by polycentricity at a small scale. These results contribute to the literature by highlighting the role of scale effect in addressing the debates about polycentricity or dispersal and provide insights for identifying urban spatial structure in planning practice.