When Bolivia became independent from Spain on 6 August 1825, it took possession of the territories that corresponded to its colonial administration in accordance with the uti possidetis juris of 1810.

With negotiations extending over a period of several decades, a decision was reached finally between Bolivia and Chile in a treaty dated 10 August 1866.

Article 1 of the treaty of 1866 stated that "the line of demarcation of boundaries between Chile and Bolivia in the desert "shall henceforth be, the parallel of latitude 24 degrees South."

In 1872, the Government of Bolivia granted a concession to a British firm to develop the nitrate deposits in Bolivian territory for a period of 15 years.

In accordance with the terms of the truce, Chile was to administer Bolivian territory from the 23rd parallel northward to the Rio Loa, thus depriving Bolivia of the northern part of the province of Antofagasta and a Pacific littoral.

Chile also recognized the right of Bolivia in perpetuity to commercial transit through its territory and ports, to be regulated by special agreements.

The provinces of Tacna and Arica, bounded north by the Rio Sama from its source in the mountains adjoining Bolivia to the sea, south by the Rio Camarones, east by Bolivia and west by the ocean, were to be administered by Chile for a 10-year period, followed by a plebiscite to determine whether the provinces would remain permanently under Chilean administration or if they would continue to be part of Peruvian territory.

Efforts to reach an agreement on the terms of a plebiscite were unsuccessful, and Chile remained in possession of Tacna and Arica after the expiration of the 10-year period stipulated in the Treaty of Ancón.

In a treaty signed at Lima on 3 June 1929, Article 2 delimited the international boundary dividing the disputed territory of Tacna and Arica between Peru and Chile.

Construction on the project was not started until 1948, and water diversion began 14 years later from a dam located about 16 miles southwest of Lago Cotacotani.

Barren rocky slopes, limited areas of short grasses, and scattered mountain shrubs are typical along the boundary.

Because of great differences in the elevation and exposure of landform features in the Andes, climatic conditions range broadly along the boundary.

Small towns serve mining companies, transportation maintenance stations, and scattered people engaged in pastoralism or limited cultivation.