Much of the urban renaissance has focused on agglomeration and the mega-city, but secondary cities also play vital roles. Greater than the sum of their parts, these cities are part of broader urban systems that have essential positions in urban migration and economic supply chains. However, as the Wilson Center notes, they’ve also struggled to attract the investment necessary to help them thrive. An overemphasis on the mega-city risks creating a negative externalities in megalopolises, while smaller cities suffer. In an urban century, a symbiotic relationship between secondary cities and their mega counterparts could enable a balance that allows many to thrive.