Tame the Waters and Hinterlands of the Intra-American Border: The Centrality of the Amazonian Waterways in the Iberian Disputes of the Treaty of Santo Ildefonso

ABSTRACT This article discusses the process of demarcation of boundaries between Portuguese and Spanish possessions, at the juncture of the Treaty of Santo Ildefonso (1777). During the process, which took place between 1780 and 1791, the rivers became important points of intra-American disputes between the Iberian demarcation commissions, since they could be taken as the natural dividing lines of the physical space subordinated to one or another monarchy, as well as ways in which the unknown localities, along with their natural resources and native populations, could be mapped. We will focus on several military incursions into the tributaries of the Negro and Japurá rivers, central to the parallel disputes between Portuguese and Spanish during the demarcations, which demonstrate the great concern with the intra-American borders of Portuguese dominions, to tame the backlands and turn them into jurisdictions.