South Buffalo Township is a township in Armstrong County, Pennsylvania, United States. The population was 2,713 at the 2020 census, an increase from the figure of 2,636 tabulated in 2010. The Allegheny River Lock and Dam No. 5 and Allegheny River Lock and Dam No. 6 are listed on the National Register of Historic Places. South Buffalo Township appear…South Buffalo Township is a township in Armstrong County, Pennsylvania, United States. The population was 2,713 at the 2020 census, an increase from the figure of 2,636 tabulated in 2010. The Allegheny River Lock and Dam No. 5 and Allegheny River Lock and Dam No. 6 are listed on the National Register of Historic Places. South Buffalo Township appears in the 1876 Atlas of Armstrong County, Pennsylvania.