[4] On July 7, 1870, a U.S. Post Office opened at the county line with Genesee County on the north side of Wilard Road at the rail tracks as Hughesville.

On February 17, 1875, Hughesville Post Office was renamed County Line.

[5] According to the United States Census Bureau, the township has a total area of 35.6 square miles (92 km2), all land.

19.9% of all households were made up of individuals, and 7.7% had someone living alone who was 65 years of age or older.

The remainder of Birch Run Township, approximately 8.5 square miles, is served by the Frankenmuth School District.

Roughly a third square mile is covered by the Clio Area School District.