Barangay Lang-ayan

Barangay Lang-ayan forms part of Santiago, a municipality in Ilocos Sur, and is classified as a very small barangay.

According to the 2020 Census of Population and Housing conducted by the Philippine Statistics Authority, Barangay Lang-ayan had a population of 402. This made it the 20th largest of 24 barangays in Santiago by population, placing it among the smaller barangays of the municipality. Residents of Barangay Lang-ayan accounted for approximately 2.06% of the total population of Santiago, which stood at 19,471 in the same census year.

The barangay recorded 373 residents in the 2015 intercensal count and 402 residents in the 2020 Census — a net change of +7.8%, consistent with a growing settlement. The Philippine Statistics Authority classifies Barangay Lang-ayan as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

Santiago is a municipality comprising 24 barangays, and serves as the governing unit directly responsible for local services in Barangay Lang-ayan, 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 Lang-ayan ranks 645th 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.

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.