Map - Chaco Province (Chaco Province)

Chaco (Wichi: To-kós-wet ), officially the Province of Chaco (provincia del Chaco ), is one of the 23 provinces in Argentina. Its capital and largest city, is Resistencia. It is located in the north-east of the country.

It 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. It also has an international border with the Paraguayan Department of Ñeembucú. With an area of 99633 km2, and a population of 1,055,259 as of 2010, it is the twelfth most extensive, and the ninth most populated, of the twenty-three Argentine provinces.

In 2010, Chaco became the second province in Argentina to adopt more than one official language. These languages are the Kom, Moqoit and Wichí languages, spoken by the Toba, Mocovi and Wichí peoples respectively. Chaco has historically been among Argentina's poorest regions, and currently ranks last both by per capita GDP and on the Human Development Index.

Chaco derives from chaku, the Quechua word used to name a hunting territory or the hunting technique used by the people of the Inca Empire.

Annually, large groups of up to thirty thousand hunters would enter the territory, forming columns and circling their prey. Jesuit missioner Pedro Lozano wrote in his book Chorographic Description of the Great Chaco Gualamba, published in Cordoba, Spain in 1733: "Its etymology indicates the multitude of nations that inhabit that region. When they go hunting, the Indians gather from many parts the vicuñas and guanacos; that crowd is called chacu in the Quechua language, which is common in Peru, and that Spaniards have corrupted into Chaco".

However, the earliest known mention of the term in a document was in a letter written to Fernando Torres de Portugal y Mesía, Viceroy of Peru, dated in 1589, by the then Governor of Tucumán, Juan Ramírez de Velasco, who referred to the region as Chaco Gualamba. (The term Gualamba is of uncertain origin and has since fallen into disuse. )