Gran Chaco

Large lowland plain in central South America, extending from southeast Bolivia, through western Paraguay to northern Argentina; area 650,000 sq km/251,000 sq mi. It consists mainly of swamps, forests (a source of quebracho timber), and grasslands, and it is utilized for cattle-raising. Oil was discovered in the 1920s in Chaco Boreal, north of the Pilcomayo River. The discovery exacerbated boundary disputes between Bolivia and Paraguay, and precipitated the Chaco War (1932–35).

The Gran Chaco is roughly divided into three regions: the Chaco Boreal extends from the Chiquitos Plains in Bolivia to the Pilcomayo River in Paraguay; the Chaco Central lies between the Pilcomayo and Bermejo rivers, mainly in Argentina; the Chaco Austral, also in Argentina, lies between the Bermejo and Salado rivers.