Barangay Casantaan

Barangay Casantaan is a mid-sized barangay in the municipality of Santo Tomas, 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 Casantaan had a population of 2,413. This made it the 6th largest of 24 barangays in Santo Tomas by population, placing it in the upper half of the municipality. Residents of Barangay Casantaan accounted for approximately 5.91% of the total population of Santo Tomas, which stood at 40,846 in the same census year.

The barangay recorded 2,137 residents in the 2015 intercensal count and 2,413 residents in the 2020 Census — a net change of +12.9%, consistent with a growing settlement. The Philippine Statistics Authority classifies Barangay Casantaan as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

Santo Tomas is a municipality comprising 24 barangays, and serves as the governing unit directly responsible for local services in Barangay Casantaan, 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 Casantaan ranks 68th 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.

The barangay's legislative and executive affairs are handled by a Punong Barangay and the Sangguniang Barangay, elected nationwide during the Barangay and SK Elections. The next BSKE is scheduled for Monday, November 2, 2026, following the synchronized election schedule set by COMELEC Resolution No. 11191.