Barangay San Francisco Sur

Barangay San Francisco Sur is a very small barangay in the municipality of San Guillermo, located in the province of Isabela, in the Cagayan Valley region of the Philippines.

According to the 2020 Census of Population and Housing conducted by the Philippine Statistics Authority, Barangay San Francisco Sur had a population of 407. This made it the 22nd largest of 26 barangays in San Guillermo by population, placing it among the smaller barangays of the municipality. Residents of Barangay San Francisco Sur accounted for approximately 1.95% of the total population of San Guillermo, which stood at 20,915 in the same census year.

Census comparisons between 2015 and 2020 show Barangay San Francisco Sur moving from 400 residents to 407 residents, an intercensal change of +1.8%. The trajectory indicates a slowly expanding community. The Philippine Statistics Authority classifies Barangay San Francisco Sur as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

San Guillermo is a municipality comprising 26 barangays, and serves as the governing unit directly responsible for local services in Barangay San Francisco Sur, including public health, sanitation, peace and order, and civil registration. Within the wider province of Isabela, which contains 1,055 barangays across its component cities and municipalities, Barangay San Francisco Sur ranks 987th by 2020 population. Isabela 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.