The United Provinces of the Rio de la Plata, (Spanish: Provincias Unidas del Rio de la Plata) also called the United Provinces of South America (Spanish: Provincias Unidas de Sud America) was the name of the union formed by most of the territories of the former Viceroyalty of the Rio de la Plata after they became independent from Spain. In 1828, the Provincia Oriental separated from the Confederation by signing the Treaty of Montevideo to become independent Uruguay after the Argentina-Brazil War. Argentina recognizes this to be its official name from 1816 to 1853, when Republica Argentina and Confederacion Argentina also became official.
See also
United Provinces of South America
Origin and history of the name of Argentina
Sources
"Simbolos Nacionales de la Republica Argentina" I.S.B.N. 950-691-036-7
