The Aconcagua River is a river in Chile that rises from the joint of two minor tributary rivers at 1,430 metres (4,700 ft) above sea level in the Andes, Juncal river from the east (which rise in the Juncal mountain) and Blanco river from the south east. Aconcagua river flows westward through a broad valley, the Valle del Aconcagua (Aconcagua's Valley), and enters the Pacific ocean 20 kilometres (12 mi) north of Valpara√≠so.
The river has a course of about 142 kilometres (88 mi), and its waters irrigate the most populous sections of the Chilean provinces of San Felipe de Aconcagua and Los Andes, being the most important economic resource of those regions. During the course of the Aconcagua river, it receives the contribution of many others rivers and swamps, reaching a mean flow of 39 cubic metres per second (1,400 cu ft/s).
The valley of Aconcagua River was used as route of Transandine Railway on Chilean side.
Although it has the same name, Aconcagua river does not rise in the slopes of the mount Aconcagua, which is entirely in Argentina about 20 kilometres (12 mi) from the beginning of the river, in the Chilean territory.