High Quality Content by WIKIPEDIA articles! Negro River (Spanish: Río Negro) means black river, and is the most important river of the Argentine province of Río Negro. The river allows the Río Negro province to produce 65% of the pears and apples of Argentina. Besides irrigation, the river is also source of hydroelectricity with small dams on its course. The river served as natural demarcation between "civilisation" and the aboriginal territories during the Conquest of the Desert of late 19th century. The river is divided into three parts: The Alto Valle (High Valley) near the beginning of the river, Valle Medio (Medium Valley) near Choele Choel, and Valle Inferior (Inferior Valley) near its end. The river crosses the steppe plains of the province through a forest of around three kilometres in the Alto Valle, and as wide as 20 kilometres towards the Valle Inferior. In the dry plain it is possible to find seashells and pebble.