Barangay San Agustin Sur

Situated in Agoo, La Union, Barangay San Agustin Sur is one of 49 barangays that make up the municipality within Ilocos Region.

According to the 2020 Census of Population and Housing conducted by the Philippine Statistics Authority, Barangay San Agustin Sur had a population of 1,169. This made it the 26th largest of 49 barangays in Agoo by population, placing it in the middle tier of the municipality. Residents of Barangay San Agustin Sur accounted for approximately 1.77% of the total population of Agoo, which stood at 66,028 in the same census year.

Census comparisons between 2015 and 2020 show Barangay San Agustin Sur moving from 1,186 residents to 1,169 residents, an intercensal change of -1.4%. The trajectory indicates a broadly stable community. The Philippine Statistics Authority classifies Barangay San Agustin Sur as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

Agoo is a municipality comprising 49 barangays, and serves as the governing unit directly responsible for local services in Barangay San Agustin Sur, including public health, sanitation, peace and order, and civil registration. Within the wider province of La Union, which contains 576 barangays across its component cities and municipalities, Barangay San Agustin Sur ranks 286th by 2020 population. La Union 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 Agustin 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.