Barangay Sinamar Sur

Barangay Sinamar Sur is a mid-sized 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 Philippine census, Barangay Sinamar Sur had a population of 2,156. This made it the 12th largest of 33 barangays in San Mateo by population, placing it in the middle tier of the municipality. Residents of Barangay Sinamar Sur accounted for approximately 3.23% of the total population of San Mateo, which stood at 66,663 in the same census year.

The barangay recorded 2,056 residents in the 2015 intercensal count and 2,156 residents in the 2020 Census — a net change of +4.9%, consistent with a growing settlement. Barangay Sinamar Sur is officially classified 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 Sinamar Sur, 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 Sinamar Sur ranks 237th 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 Sinamar Sur 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.