[4] South Buffalo Township appears in the 1876 Atlas of Armstrong County, Pennsylvania.

[5] South Buffalo Township is located near the southwestern corner of Armstrong County.

North Buffalo Township is to the north, and the borough of Freeport abuts the southwestern edge of the township in the triangle between the Allegheny River and Butler County.

Buffalo Creek flows through the western part of the township, joining the Allegheny at Freeport.

The racial makeup of the township was 99.21% White, 0.14% African American, 0.04% Asian, and 0.61% from two or more races.

17.4% of all households were made up of individuals, and 9.2% had someone living alone who was 65 years of age or older.