Río Negro,provincia (province), south-centralArgentina. It lies within the region ofPatagonia and extends westward from theAtlantic Ocean to theAndes Mountains and the border withNeuquén province.Viedma, in the east, is theprovincial capital.

The province is crossed (northwest to southeast) by theNegro River. South of the Negro, most of the land consists of arid tablelands. To the west are the chains of lakes and the forested valleys of the Andes, the site ofNahuel Huapí National Park. The Atlantic coastline has one deep indentation, the Gulf of San Matías, in the northern bend of which is the small port of San Antonio Oeste.

The area was settled in 1782 by the explorer Basilio Villarino and was made a national territory in 1884. It became a province in 1955. A dam, built on the Negro River nearNeuquén, made possible the irrigation of a large area between theColorado (the province’s northern boundary) and Negro rivers, where alfalfa is grown, pears and apples are produced for export, and sheep are raised. The Sierra Grande mining and industrial complex was developed during the 1970s. Viedma is located near the mouth of the Negro River and on the railway that runs inland fromSan Antonio Oeste toSan Carlos de Bariloche, a resort on the shore ofLake Nahuel Huapí. Area 78,384 square miles (203,013 square km). Pop. (2001) 552,822; (2010) 638,645.