Barangay Ballacayu

Situated in San Pablo, Isabela, Barangay Ballacayu is one of 17 barangays that make up the municipality within Cagayan Valley.

According to the 2020 Census of Population and Housing conducted by the Philippine Statistics Authority, Barangay Ballacayu had a population of 2,184. This made it the 4th largest of 17 barangays in San Pablo by population, placing it in the upper half of the municipality. Residents of Barangay Ballacayu accounted for approximately 8.30% of the total population of San Pablo, which stood at 26,320 in the same census year.

Between the 2015 and 2020 censuses, the population of Barangay Ballacayu changed from 2,242 to 2,184, a shift of -2.6% over the five-year period. This places the barangay among those with contracting populations in San Pablo. The Philippine Statistics Authority classifies Barangay Ballacayu as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

San Pablo is a municipality comprising 17 barangays, and serves as the governing unit directly responsible for local services in Barangay Ballacayu, 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 Ballacayu ranks 232nd 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.