Cerro Largo Department in the context of Melo, Uruguay

Rio Grande do Sul (UK: /ˌriːuː ˌɡrændi duː ˈsʊl/, US: /- ˌɡrɑːndi duː ˈsuːl/; Portuguese: [ˈʁi.u ˈɡɾɐ̃dʒ(i) du ˈsuw] ; lit. "Great River of the South") is a state in the southern region of Brazil. It is the fifth-most populous state and the ninth-largest by area and it is divided into 497 municipalities. Located in the southernmost part of the country, Rio Grande do Sul is bordered clockwise by Santa Catarina to the north and northeast, the Atlantic Ocean to the east, the Uruguayan departments of Rocha, Treinta y Tres, Cerro Largo, Rivera, and Artigas to the south and southwest, and the Argentine provinces of Corrientes and Misiones to the west and northwest. The capital and largest city is Porto Alegre. The state has the highest life expectancy in Brazil, and the crime rate is relatively low compared to the Brazilian national average. The state has 5.4% of the Brazilian population and it is responsible for 6.6% of the Brazilian GDP.

The state shares a gaucho culture with its neighbors Argentina and Uruguay. Before the arrival of Portuguese and Spanish settlers, it was inhabited mostly by the Guarani and Kaingang peoples (with smaller populations of Charrúa and Minuane). The first Europeans there were Jesuits, followed by settlers from the Azores. In the 19th century it was the scene of conflicts including the Ragamuffin War and the Paraguayan War. Large waves of German and Italian migration have shaped the state as well.

The 2024 Rio Grande do Sul floods were severe floods caused by heavy rains and storms that hit the Brazilian state of Rio Grande do Sul, and the adjacent Uruguayan cities of Treinta y Tres, Paysandú, Cerro Largo, and Salto. From 29 April through to May, it resulted in 181 fatalities (as of 7 July 2024), widespread landslides, and a dam collapse. It is considered the country's worst flooding in over 80 years.

The floods marked the fourth such environmental disaster in Brazil within the past 12 months, following similar calamities that killed 75 people in July, September, and November 2023.

Treinta y Tres (Spanish pronunciation: [ˈtɾejnta‿j ˈtɾes]) is a department of Uruguay. Its capital is Treinta y Tres. It is located in the east of the country, bordering the departments of Cerro Largo to the north; Durazno and Florida to the west; Lavalleja and Rocha to the south; while to its east is the lake Laguna Merín, separating it from the southernmost end of Brazil. With a total population of 47,706, it is the second-least populated department in Uruguay (ahead of Flores) and the third-least densely populated, behind Durazno and Flores.

Rivera Department (Spanish pronunciation: [riˈβeɾa]) is a department of the northern region of Uruguay. It has an area of 9,370 km (3,620 sq mi) and a population of 109,300. Its capital is the city of Rivera. It borders Brazil to the north and east, Cerro Largo Department to the southeast, Tacuarembó Department to the south and west and Salto Department to the northwest.

Tacuarembó (Spanish pronunciation: [takwaɾemˈbo]) is the largest department of Uruguay and it is part of its northern region. Its capital is Tacuarembó. It borders Rivera Department to its north and east, the departments of Salto, Paysandú and Río Negro to its west and has the river Río Negro flowing along its south border, separating it from the departments of Durazno and Cerro Largo.

Durazno (Spanish pronunciation: [duˈɾasno]; Uruguayan Spanish: [duˈɾahno]) is a department of Uruguay. Its capital is Durazno. Its name means "peach" in Spanish, referring to the department's peaches and its status as an agricultural breadbasket. It is located in the centre of the country, and is bounded to the north by the Río Negro and the Río Yi to the South. To its north are the departments of Río Negro and Tacuarembó, to it southeast the departments of Treinta y Tres, to its south the departments of Flores and Florida, while on its east is the department of Cerro Largo.