Uruguay has one of the shorter land borders in South America, with a total length of 972 miles. Uruguay shares its land border with two countries: Argentina and Brazil. The border was first demarcated in the 19th century, when Uruguay was established as an independent country.
Brazil borders Uruguay to the north and the east of the country. The international border is the longest that Uruguay shares with another country, stretching a total of 612 miles in length. The border starts at the mouth of the Arroyo Chui, from where it extends until it ends at the Argentina-Uruguay-Brazil tri-point. A significant portion of the border follows the Quarai River and the Lagoa Mirim lagoon. The border was first established in the mid-19th century, as was provided by the 1851 Boundary Treaty, an international agreement signed by the two countries, which was also a precursor of the independence of Uruguay. The treaty was made as Uruguay was just emerging from bloody civil war; the Uruguayan Civil War, one that Brazil played a significant role to see its end. Uruguay recognized that the assistance from Brazil granted them victory over the Blancos and agreed to cede part of its territory as gratitude. The region north of River Quarai which was initially part of Uruguay was transferred to become part of Brazil territory. However, the treaty did not explicitly state the ownership of a small section near Masoller known as Rincon de Artigas, whose sovereignty has been challenged by the two countries. Currently, the controversial portion is under the administration of Brazil.
Argentina is one of the two countries that border Uruguay and is situated west of the country. The two countries share a long land border, which stretches about 360 miles in length, making it the shortest of Uruguay’s international borders. The tri-point connecting Uruguay, Argentina and Brazil represent the start of the border, from where it follows the Uruguay River until it meets the confluence of the Rio de la Plata and River Parana. Buenos Aires, Corrientes, and Entre Rios are the three provinces in Argentina touched by the border, while in Uruguay the border touches six departments, which are the Rio Negro, Artigas, Colonia, Paysandu, Soriano, and Salto. The border has always been defined by the Uruguay River, and predates the establishment of the Republic of Uruguay, as it separates the Viceroyalty of Rio de la Plata of the Eastern Band. The two countries have clashed in the past over a territorial dispute concerning the building on the Uruguay River of pulp mills. The issue strained diplomatic relations between the two bordering countries and threatened to sever the long-standing socioeconomic corporation between the two countries. The case was even presented before the International Court of Justice, which ruled against the closing of the pulp factory. The two countries, however, resolved the issue in 2010 after they agreed to institute joint coordination of the operations in the Uruguay River, ending the territorial dispute.