This article seeks to better understand patterns of municipal incorporation in southern California between 1950 and 2010. Existing literature explains municipal fragmentation as a debate about efficiency versus social justice or the result of local conflicts over land use and race. This article explores the dynamics of local-state relations relevant to municipal incorporation in California. The state’s role in creating southern California as a ‘fragmented metropolis’ from 1953–1992 is contrasted with an era of fiscal federalism from 1992–2010, when far fewer cities were created. Recent case studies of incorporation attempts in San Fernando Valley and East Los Angeles are examined. It is argued that state policies—especially in the area of municipal finance—have been critical in shaping patterns of municipal incorporation in southern California.