Which river separates the countries of Argentina and Uruguay?

The river that separates Argentina and Uruguay is the Uruguay River. It forms much of the international boundary between the two countries before flowing into the Río de la Plata.

The Uruguay River begins in southern Brazil, where the Canoas and Pelotas rivers meet, and runs roughly 1,838 kilometres southward. Along its course, it also helps define parts of Brazil’s borders with Argentina and Uruguay. Its name is derived from Guaraní, although the exact meaning is debated.

The river is part of the Río de la Plata basin, one of South America’s major drainage systems. Near its mouth, it joins the Paraná River to form the broad Río de la Plata estuary. This is why the Paraná is a common mix-up: it meets the Uruguay River, but it does not separate Argentina and Uruguay.

The Uruguay River has also been important for transport, hydroelectric power and diplomacy. The Salto Grande dam and several international bridges connect communities on opposite banks.