[4] It contained 718 housing units.

Smithfield Township was named for Isaac B. Smith, a pioneer settler.

[5] According to the 2010 census, the township has a total area of 35.09 square miles (90.9 km2), of which 34.99 square miles (90.6 km2) (or 99.72%) is land and 0.1 square miles (0.26 km2) (or 0.28%) is water.

[4] Cedar Lake is in this township.

The township contains two cemeteries: Barkers Chapel and Cedar Lake.