As of the 2020 census, its population was 4,016 (down from 4,063 at 2010[3]) and it contained 1,682 housing units.

It was named for Territorial Governor Thomas Posey.

[5] According to the 2010 census, the township has a total area of 35.75 square miles (92.6 km2), of which 35.04 square miles (90.8 km2) (or 98.01%) is land and 0.71 square miles (1.8 km2) (or 1.99%) is water.

[3] (This list is based on USGS data and may include former settlements.)

The township contains seven cemeteries: Billtown, Clearview, Cottage Hill, German, Rhule, Summit Lawn and Summit Lawn.