The Province of Chaco (Spanish: provincia del Chaco, Spanish pronunciation: [ˈtʃako]) is a province in northeastern Argentina. With an area of 99,633 km² (38,469 sq mi) and a population of 1,055,259 as of 2010, it is the 12th most extensive and the 9th most populated of the 23 Argentine provinces. Chaco is bordered by Salta and Santiago del Estero to the west, Formosa to the north, Corrientes to the east, and Santa Fe to the south. The province also has an international border with the Paraguayan Department of Ñeembucú.