Located in the northeastern part of the county, it borders the following townships: •
Walnut Township, Gallia County - north •
Harrison Township, Gallia County - northeast corner •
Guyan Township, Gallia County - east •
Rome Township - southeast corner •
Windsor Township - south •
Lawrence Township - southwest corner •
Aid Township - west •
Symmes Township - northwest corner No municipalities are located in Mason Township. Established before 1873,
Arabia is a populated place in the township.
Yarico is also a populated place in the township. ==Name and history==