Incorporated as a borough in September of 1877, it was originally part of Lower St. Clair Township. The area was named for Jeremiah Knox, a fruit farmer known for his strawberries who settled there in the early 1800’s. The area was desirable for agriculture as it was shielded from the smokey factories and mills located closer to Pittsburgh on the South Side. Knox began to sell off his farm for development in the 1870’s, and the introduction of the Mt. Oliver incline, along with The Pittsburgh, Knoxville and St. Clair Electric Railroad provided easier access for families settling in the area.
The Knoxville Incline was constructed in 1890, running between the South Side, Allentown and the area. This was one of only 2 curved inclines, and allowed for even greater development of the area. The incline was in operation until 1960, when it was demolised. The old rail bed can still be seen today.
The city of Pittsburgh annexed the neighborhood in 1927.