The township is located on the west slope of Laurel Ridge mountain.

Donegal was one of the original townships established in Westmoreland County in 1773.

According to historian John Boucher, its original boundaries were much larger, constituting the majority of the Ligonier valley and extending into what is now Fayette County.

[7] At the 2000 census there were 2,442 people, 950 households, and 691 families living in the township.

Logging was a major industry in Donegal Township in the early 1900s.

The underground deep mine employed about 100 people as of January 2022.

Attempts to extend the permit and expand operations in 2022 met with controversy.