Barangay Santiago

Barangay Santiago is a small barangay in the municipality of Reina Mercedes, located in the province of Isabela, in the Cagayan Valley region of the Philippines.

According to the 2020 Philippine census, Barangay Santiago had a population of 1,090. This made it the 13th largest of 20 barangays in Reina Mercedes by population, placing it in the middle tier of the municipality. Residents of Barangay Santiago accounted for approximately 3.91% of the total population of Reina Mercedes, which stood at 27,900 in the same census year.

Between the 2015 and 2020 censuses, the population of Barangay Santiago changed from 1,094 to 1,090, a shift of -0.4% over the five-year period. This places the barangay among those with broadly stable populations in Reina Mercedes. Barangay Santiago is officially classified as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

Reina Mercedes is a municipality comprising 20 barangays, and serves as the governing unit directly responsible for local services in Barangay Santiago, including public health, sanitation, peace and order, and civil registration. Within the wider province of Isabela, which contains 1,055 barangays across its component cities and municipalities, Barangay Santiago ranks 597th by 2020 population. Isabela is classified as a 1st by the Bureau of Local Government Finance, a category that reflects the province's annual regular income.

Barangay Santiago is governed by an elected Sangguniang Barangay composed of a Punong Barangay and seven kagawads, with the Sangguniang Kabataan representing the youth. The next BSKE, set for Monday, November 2, 2026, will elect officials to four-year terms as provided under Republic Act No. 12232.