When Somerset County was established in 1795 Quemahoning was one of the six original townships.

The name is a Native American name meaning "pine tree lick,"[3] with "cuuni" indicating a pine grove and "mahoni" meaning water from a lick.

[4] The Trostletown Bridge was added to the National Register of Historic Places in 1980.

As of the census[7] of 2000, there were 2,180 people, 827 households, and 627 families residing in the township.

21.5% of all households were made up of individuals, and 10.2% had someone living alone who was 65 years of age or older.