The territory of the province was part of the Duarte province and then it was made a municipality of the Samaná province. In 1958, it was made a province with the name "Julia Molina", after the mother of the dictator Rafael Trujillo, with the municipalities of Julia Molina and Cabrera and the municipal district, later a municipality, of Río San Juan. In 1961, after Trujillo's death, the province was given the present name and the capital was named Nagua.