The Pilcomayo is a river rising in the Bolivian Andes, east of Lake Poopó, flowing over 700 miles across Chaco into the Paraguay River near Asunción. Near Chaco, it serves as the border between Argentina and Paraguay. Note that the geology in this article currently reflects views from the first decade of the 20th century. ... There are things that have the name Chaco: South America: Gran Chaco, a region in South America Chaco Province, Argentina in the northeastern part of the country Chaco, a region in Paraguay Chaco Department, historical in Paraguay and proposed in Bolivia Gran Chaco Province, Bolivia (in Tarija Department) Chaco War... The Paraguay River near Asunción The River Paraguay is a major river in South America, running from west Brazil south through the centre of Paraguay to flow into the River Parana. ... Map of Paraguay Panteón de los Héroes in Asunción Asunción, population 500,939 (1992), is the capital of Paraguay. ...