San José is one of the nineteen departments that make up the Eastern Republic of Uruguay. Its capital is San José de Mayo. It is located in the southwest of the country, bounded on the north by Flores, on the east by Florida, Canelones and Montevideo, on the south by the Plata River that separates it from the Argentine Republic, on the west by Colonia and on the northwest by Soriano. With 4,992 km² it is the fourth least extensive department-ahead of Maldonado, Canelones and Montevideo, the least extensive- and with 21.70 inhabitants / km² it is the fourth most densely populated-behind Montevideo, Canelones and Maldonado.
Its southern fringe is part of the Metropolitan Area of Montevideo, because this area is occupied by the expansion of the urban sprawl of Greater Montevideo.