Colchagua, a province of central Chile, bounded N. by Santiago and O’Higgins, E. by Argentina, S. by Curicó, and W. by the Pacific. Its area is officially estimated at 3856 sq. m.; pop. (1895) 157,566. Extending across the great central valley of Chile, the province has a considerable area devoted to agriculture, but much attention is given to cattle and mining. Its principal river is the Rapel, sometimes considered as the southern limit of the Inca empire. Its greatest tributary is the Cachapoal, in the valley of which, among the Andean foothills, are the popular thermal mineral baths of Cauquenes, 2306 ft. above sea-level. The state central railway from Santiago to Puerto Montt crosses the province and has two branches within its borders, one from Rengo to Peumo, and one from San Fernando via Palmilla to Pichilemu on the coast. The principal towns are the capital, San Fernando, Rengo and Palmilla. San Fernando is one of the several towns founded in 1742 by the governor-general José de Manso, and had a population of 7447 in 1895. Rengo is an active commercial town and had a population of 6463 in 1895.