How do property rights evolve when unoccupied areas attract economic use? Who are the first claimants on the frontier and how do they establish their property rights? When do governments provide de jure property rights? We present a conceptual framework that addresses these questions and apply it to the frontiers of Australia, the United States, and Brazil. Our framework stresses the crucial role of politics as frontiers develop by identifying situations where the competition for land by those with de facto rights and those with de jure rights leads to violence or potential conflicts.