Buenos Aires, officially the Buenos Aires Province, is the largest and most populous Argentine province. It takes its name from the city of Buenos Aires, the capital of the country, which used to be part of the province and the province's capital until it was federalized in 1880. Since then, in spite of bearing the same name, the province does not include Buenos Aires city, though it does include all other parts of the Greater Buenos Aires metropolitan area. The capital of the province is the city of La Plata, founded in 1882.

Entre Ríos is a central province of Argentina, located in the Mesopotamia region. It borders the provinces of Buenos Aires (south), Corrientes (north) and Santa Fe (west), and Uruguay in the east.