[4] The township is named for the hero of the American Revolution and the first President of the United States, George Washington.

Historically, two trails of the native indigenous peoples ran along parts of White Deer Hole Creek in Washington Township.

They returned, and the creek served as the southern boundary of Lycoming County and Washington Township when it was formed in 1795.

The Great Island Path was a major trail that ran north along the Susquehanna River from the Saponi village of Shamokin at modern Sunbury, fording the West Branch of the Susquehanna there and following the west bank of the river north until the White Deer Hole valley.

The path turned west at Allenwood and followed White Deer Hole Creek until about the present location of Elimsport in Washington Township.

There it headed northwest, crossed North White Deer Ridge and passed west through the Nippenose Valley, then turned north and crossed Bald Eagle Mountain via McElhattan Creek and ran along the south bank of the West Branch to the Great Island (near the present day city of Lock Haven).

[5] In the Revolutionary War, settlements throughout the Susquehanna valley were attacked by Loyalists and Native Americans allied with the British.

Settlers abandoned their homes and fields, drove their livestock south, and towed their possessions on rafts on the river to Sunbury.

[6] Beginning with the first settlers, much of the land along White Deer Hole Creek in Washington Township was slowly cleared of timber.

The railroad was torn up, and its one second-hand Shay locomotive was moved to the Vincent Lumber Company operation at Denholm in Juniata County.

[8] On May 31, 1985, around 10:30 pm, a tornado tore through the eastern part of the township, went through the State Gamelands (Old Alvira), and continued into Union County with no warning.

[9] Despite this small-scale lumbering, as of 2006 the forests have grown back and are mixed oak, with blueberry and mountain laurel bushes.