Barangay San Mariano

Barangay San Mariano forms part of Loreto, a municipality in Agusan Del Sur, and is classified as a mid-sized barangay.

According to the 2020 Census of Population and Housing conducted by the Philippine Statistics Authority, Barangay San Mariano had a population of 2,501. This made it the 7th largest of 17 barangays in Loreto by population, placing it in the middle tier of the municipality. Residents of Barangay San Mariano accounted for approximately 5.70% of the total population of Loreto, which stood at 43,880 in the same census year.

Between the 2015 and 2020 censuses, the population of Barangay San Mariano changed from 2,411 to 2,501, a shift of +3.7% over the five-year period. This places the barangay among those with growing populations in Loreto. The Philippine Statistics Authority classifies Barangay San Mariano as rural, a designation applied to barangays with lower population density and predominantly non-built-up land use.

Loreto is a municipality comprising 17 barangays, and serves as the governing unit directly responsible for local services in Barangay San Mariano, including public health, sanitation, peace and order, and civil registration. Within the wider province of Agusan Del Sur, which contains 314 barangays across its component cities and municipalities, Barangay San Mariano ranks 90th by 2020 population. Agusan Del 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.