Barangay Casilagan

Barangay Casilagan is a small barangay in the municipality of Narvacan, located in the province of Ilocos Sur, 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 771. This made it the 28th largest of 34 barangays in Narvacan by population, placing it among the smaller barangays of the municipality. Residents of Barangay Casilagan accounted for approximately 1.67% of the total population of Narvacan, which stood at 46,234 in the same census year.

The barangay recorded 647 residents in the 2015 intercensal count and 771 residents in the 2020 Census — a net change of +19.2%, 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.

Narvacan is a municipality comprising 34 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 Ilocos Sur, which contains 768 barangays across its component cities and municipalities, Barangay Casilagan ranks 380th by 2020 population. Ilocos Sur 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.