Barangay Casilagan

Classified as a very small barangay, Barangay Casilagan is one of the administrative divisions of Nagbukel in Ilocos Sur, Ilocos Region, Philippines.

According to the 2020 Census of Population and Housing conducted by the Philippine Statistics Authority, Barangay Casilagan had a population of 330. This made it the 10th largest of 12 barangays in Nagbukel by population, placing it among the smaller barangays of the municipality. Residents of Barangay Casilagan accounted for approximately 6.04% of the total population of Nagbukel, which stood at 5,465 in the same census year.

Census comparisons between 2015 and 2020 show Barangay Casilagan moving from 308 residents to 330 residents, an intercensal change of +7.1%. The trajectory indicates a growing community. 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.

Nagbukel is a municipality comprising 12 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 685th 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.

Barangay Casilagan is governed by an elected Sangguniang Barangay composed of a Punong Barangay and seven kagawads, with the Sangguniang Kabataan representing the youth. The next BSKE, set for Monday, November 2, 2026, will elect officials to four-year terms as provided under Republic Act No. 12232.