Paraguay is bounded by three substantially larger countries: Bolivia, Argentina, and Brazil (see fig. 1). The northwestern boundary with Bolivia, extending through the low hills of the Chaco region, was set in 1938. The boundary between the Chaco and Brazil was defined in 1927 it continues from the confluence of the Río Apa and Río Paraguay northward along the course of the Río Paraguay to the border with Bolivia. The northern border of the Paraneña region, set in 1872, follows the course of the Río Paraná, the ridges of the mountains in the northeast region, and finally the course of the Río Apa until it empties into the Río Paraguay. Paraguay's southern border with Argentina is formed by the Río Pilcomayo, Río Paraguay, and Río Paraná. These boundaries were agreed to in 1876.

Data as of December 1988