The Department of Junín is in the center-north of the province of MendozMendozantine Republic, 54 km towards the east of the City of Mendoza. It is limited in the west by Luján – by the last hills of the Cordón del Carrizal, those which are comprised on the Mountainous area of the Huayquerías. In the northwest, the limit is with Maipú – with the Arroyo Claro. In the east, it is by the Llanura de Travesía. This is the arid sector of the department, with small dunes; to the north and the northeast by San Martín; in the south by Rivadavia, in the southeast by Santa Rosa, and in the southwest by the Tunuyán River, that provides the waters that irrigate great part of the department.
The climate is arid and temperate, with the predominance of sunny days and almost no cloudiness.
From the Gobernador Benegas water reservoir, located in the far southwest end, begins the well known inferior flow of the Tunuyán River that, with an average volume of 33 m3 per second, is totally used for irrigation of the departments of the East Region through an ample system of channels. The existence of this network has been fundamental for the transformation of the panorama and the economy of Junín.
The territory of Junín has only scarce specimens of its natural vegetation, in which predominate the sweet carob tree, jarilla (a bush), zampa, piquillín, retamo, jume. In addition, in the riverbanks there are cortaderas, carrizos and junquillos.