Santiago, officially the Municipality of Santiago, is a municipality in the province of Ilocos Sur, Philippines. According to the 2020 census, it h…Santiago, officially the Municipality of Santiago, is a municipality in the province of Ilocos Sur, Philippines. According to the 2020 census, it has a population of 19,471 people. The town was named in honor of Saint James. One of the town's attractions, Santiago Cove, is dubbed as the "Boracay of Ilocos Sur" because of its white sand.