Barangay San Antonio

Classified as a small barangay, Barangay San Antonio is one of the administrative divisions of San Mateo in Isabela, Cagayan Valley, Philippines.

According to the 2020 Philippine census, Barangay San Antonio had a population of 1,093. This made it the 27th largest of 33 barangays in San Mateo by population, placing it among the smaller barangays of the municipality. Residents of Barangay San Antonio accounted for approximately 1.64% of the total population of San Mateo, which stood at 66,663 in the same census year.

The barangay recorded 1,137 residents in the 2015 intercensal count and 1,093 residents in the 2020 Census — a net change of -3.9%, consistent with a contracting settlement. Barangay San Antonio 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 San Antonio, 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 Antonio ranks 596th 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 Antonio 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.