Rosario is a municipality located in Ilocos Sur province in the Ilocos region of the Philippines. The municipality is situated on the western coast of Luzon island, facing the South China Sea.
As a municipality in Ilocos Sur, Rosario is part of a region known for its historical significance in Philippine history and its distinctive cultural heritage. The Ilocos region has a long tradition of weaving, agriculture, and fishing communities. The municipality's economy is likely based on coastal fishing and agricultural activities typical of municipalities in the Ilocos province.