Barangay Nagcullooban

Situated in Sinait, Ilocos Sur, Barangay Nagcullooban is one of 44 barangays that make up the municipality within Ilocos Region.

According to the 2020 Census of Population and Housing conducted by the Philippine Statistics Authority, Barangay Nagcullooban had a population of 438. This made it the 28th largest of 44 barangays in Sinait by population, placing it in the middle tier of the municipality. Residents of Barangay Nagcullooban accounted for approximately 1.68% of the total population of Sinait, which stood at 25,998 in the same census year.

Between the 2015 and 2020 censuses, the population of Barangay Nagcullooban changed from 433 to 438, a shift of +1.2% over the five-year period. This places the barangay among those with slowly expanding populations in Sinait. The Philippine Statistics Authority classifies Barangay Nagcullooban as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

Sinait is a municipality comprising 44 barangays, and serves as the governing unit directly responsible for local services in Barangay Nagcullooban, 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 Nagcullooban ranks 628th 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.