This research engages the (re)configuration of popular identities in the making of Argentinean and Chilean Patagonia. Triple frontier ('civilizational', internal and international), it was occupied and then populated by Chilote indigenous and European seasonal and permanent settlers following the native's genocide. This project maintains that borderlands constitute a 'revolutionary space' where the cultural revolution state-making implies resulted from the emergence of multiple, contested sovereignties -not just territorial, but social. Thus, I will analyze the changing hierarchies that local racial, class and national categorizations and identities experienced in their relation with the centralizing and homogenizing policies of the competing States. Dealing with a wide variety of sources this research avoids metropolitan-centered approaches to nation-State building, focusing on the historical experiences of multiethnic subjects and the peripherical exchanges pervading the states' social boundary making. My dissertation aims to provide the first transnational and comparative social history of nation-State formation in the Southern Cone, analyzing eight interrelated processes: 1) the racial and geopolitical considerations involved in the decision-making process regarding Patagonia's occupation since 1840; 2) the relation between racialization of the native population and land property regimes furthered by both Argentina and Chile; 3) the formation of the local, transnational oligopoly in/and its relation with the metropolitan elites; 4) the policies and networks of migration, the formation of regional identities across 'racial' and national lines and the prevalence of class groupings in front of the politics of Chileanization and Argentinization; 5) the racializations deployed by metropolitan travelers regarding the 'ever incomplete' project of 'national races' building in Patagonia; 6) the racial, class and national subtexts inscribed in the judiciary positivism;