Barangay Gayong-Gayong Sur

Classified as a small barangay, Barangay Gayong-Gayong Sur is one of the administrative divisions of City of Ilagan in Isabela, Cagayan Valley, Philippines.

According to the 2020 Census of Population and Housing conducted by the Philippine Statistics Authority, Barangay Gayong-Gayong Sur had a population of 1,256. This made it the 50th largest of 91 barangays in City of Ilagan by population, placing it in the middle tier of the city. Residents of Barangay Gayong-Gayong Sur accounted for approximately 0.79% of the total population of City of Ilagan, which stood at 158,218 in the same census year.

Census comparisons between 2015 and 2020 show Barangay Gayong-Gayong Sur moving from 1,204 residents to 1,256 residents, an intercensal change of +4.3%. The trajectory indicates a growing community. The Philippine Statistics Authority classifies Barangay Gayong-Gayong Sur as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

City of Ilagan is a city comprising 91 barangays, and serves as the governing unit directly responsible for local services in Barangay Gayong-Gayong 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 Gayong-Gayong Sur ranks 517th 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.