ocated along the western coast of Northern Luzon, the municipality of Santiago lies between 17º 15º to 20º and 120º 15º to 30º east. The municipality is bounded on the north by the municipalities of San Esteban and Burgos, on the east by the municipalities of Banayoyo and Lidlidda, on the south by the City of Candon. To the west Santiago faces the Philippine Sea (China Sea). It is about 49 kilometers from Vigan City and 358 kilometers from Manila.

Santiago has a total land area of 74.5 square kilometers divided among 24 barangays, two (2) of which are Poblaciones. Santiago is predominantly an agricultural municipality with approximately 3,203 hectares, representing 80 % of land tillers. The principal agricultural products include palay, tobacco, vegetables, root crops and others. Tobacco is the town’s most valuable agricultural product.

A big part of the municipality ‘s land area s covered by forest. This supports a thriving industry of various forest products that include wood, bamboo, sawali and others. Wildlife such as wild chicken, pig, deer and the like have become extinct due to frequent hunting and deforestation by means of the kaingin system.

Fishing is another important industry of Santiago. The barangays of Ambucao, Sabangan, Guinabang, San Roque, Gabao and Butol are the municipality’s richest fishing grounds. A fishing port-warf was constructed in Barangay Sabangan in order to boast the fishing industry in the municipality as well as the entire province.