Beginning at the estuary of the Rio de la Plata, the boundary line ascends the Uruguay river, on the eastern side of the strategically important island of Martin Garcia, to the mouth of the Pequiry, thence under the award of President Grover Cleveland in 1894 up that small river to its source and in a direct line to the source of the Santo Antonio, a small tributary of the Iguassu, thence down the Santo Antonio and Iguassu to the upper Parana, which forms the southern boundary of Paraguay.
Beginning at the mouth of the Quarahy, the boundary line between Brazil and Argentina ascends the Uruguay, crosses to the source of the Santo Antonio, and descends that small stream and the Iguassu to the Parana, where it terminates.
Pop. (1905 estimate), 631,347, including 50,000 Iguassu Indians; area, about 97,700 sq.
This line was defined by the treaty of 1857, and by the decision of President Cleveland in 1895 with regard to the small section between the Uruguay and Iguassu rivers.