Barangay Casilagan

Barangay Casilagan is a small barangay in the municipality of San Juan, located in the province of La Union, in the Ilocos Region region of the Philippines.

According to the 2020 Census of Population and Housing conducted by the Philippine Statistics Authority, Barangay Casilagan had a population of 933. This made it the 15th largest of 41 barangays in San Juan by population, placing it in the middle tier of the municipality. Residents of Barangay Casilagan accounted for approximately 2.30% of the total population of San Juan, which stood at 40,507 in the same census year.

The barangay recorded 851 residents in the 2015 intercensal count and 933 residents in the 2020 Census — a net change of +9.6%, consistent with a growing settlement. The Philippine Statistics Authority classifies Barangay Casilagan as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

San Juan is a municipality comprising 41 barangays, and serves as the governing unit directly responsible for local services in Barangay Casilagan, 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 Casilagan ranks 385th 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 Casilagan 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.