Barangay San Marcos

Barangay San Marcos is a small barangay in the municipality of San Mateo, located in the province of Isabela, in the Cagayan Valley region of the Philippines.

According to the 2020 Census of Population and Housing conducted by the Philippine Statistics Authority, Barangay San Marcos had a population of 1,821. This made it the 18th largest of 33 barangays in San Mateo by population, placing it in the middle tier of the municipality. Residents of Barangay San Marcos accounted for approximately 2.73% of the total population of San Mateo, which stood at 66,663 in the same census year.

The barangay recorded 1,622 residents in the 2015 intercensal count and 1,821 residents in the 2020 Census — a net change of +12.3%, consistent with a growing settlement. The Philippine Statistics Authority classifies Barangay San Marcos as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

San Mateo is a municipality comprising 33 barangays, and serves as the governing unit directly responsible for local services in Barangay San Marcos, 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 San Marcos ranks 319th 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.

Like every Philippine barangay, Barangay San Marcos is led by an elected Punong Barangay (barangay captain) supported by seven Sangguniang Barangay members (kagawads), an SK Chairperson, a Barangay Secretary, and a Barangay Treasurer. The next Barangay and Sangguniang Kabataan Elections (BSKE) are scheduled for Monday, November 2, 2026, with officials serving four-year terms under Republic Act No. 12232.