Barangay San Isidro Sur

Barangay San Isidro Sur forms part of Luna, a municipality in Apayao, and is classified as a small barangay.

According to the 2020 Philippine census, Barangay San Isidro Sur had a population of 1,708. This made it the 2nd largest of 22 barangays in Luna by population, placing it among the most populous barangays of the municipality. Residents of Barangay San Isidro Sur accounted for approximately 8.02% of the total population of Luna, which stood at 21,297 in the same census year.

Between the 2015 and 2020 censuses, the population of Barangay San Isidro Sur changed from 1,545 to 1,708, a shift of +10.6% over the five-year period. This places the barangay among those with growing populations in Luna. Barangay San Isidro Sur is officially classified as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

Luna is a municipality comprising 22 barangays, and serves as the governing unit directly responsible for local services in Barangay San Isidro Sur, including public health, sanitation, peace and order, and civil registration. Within the wider province of Apayao, which contains 133 barangays across its component cities and municipalities, Barangay San Isidro Sur ranks 12th by 2020 population. Apayao is classified as a 3rd 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.