As of the 2020 census, its population was 16,054 (up from 15,534 at 2010[3]) and it contained 6,811 housing units.

[4] Washington Township was organized on 12 May 1817 at the first meeting of the Daviess County Commissioners.

Among its earliest settlements was the community of Liverpool, which later became subsumed into the county seat of Washington, which is located in Washington Township.

45, Jefferson Elementary School, and Prairie Creek Site are listed on the National Register of Historic Places.

The township contains five cemeteries: Colbert, Hawkins, New Veale Creek, Oak Grove and Saint Johns.