Buenos Aires and Montevideo are situated across the banks of _________.

Buenos Aires, the capital of Argentina, and Montevideo, the capital of Uruguay, are situated on the banks of the Río de la Plata, also known as the River Plate [3]. This body of water is a funnel-shaped estuary formed by the confluence of the Paraná and Uruguay rivers. It serves as a natural border between Argentina and Uruguay. The estuary is a critical maritime gateway; Buenos Aires is located on its western/southern shore, while Montevideo is situated on the eastern/northern shore [2]. The River Plate is noted for being one of the widest river systems in the world, reaching a width of approximately 220 kilometers at its mouth. While the Orinoco, Purus, and Madeira rivers are major South American waterways, they are located significantly further north in Venezuela and the Amazon basin.

Sources

1. [1] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 10: Coastal Landforms > Types of Coast > p. 94
2. [3] https://en.wikipedia.org/wiki/R%C3%ADo_de_la_Plata
3. [2] https://www.britannica.com/place/Rio-de-la-Plata/History