Lumbering was the dominant industry in Penn Township during the mid-to-late 19th century.

U.S. Route 220 crosses the northernmost part of the township in the Muncy Creek valley, leading northeast to Towanda and southwest to Hughesville and Williamsport, the Lycoming county seat.

[1] The northern and western parts of the township drain to Muncy Creek, which forms the northern border of the township and flows southwestward to the West Branch Susquehanna River near Muncy.

The southern and eastern parts of the township, including Beaver Lake, drain south into Franklin Township to Little Muncy Creek, a tributary of Muncy Creek.

The racial makeup of the township was 98.89% White, 0.44% Asian, and 0.67% from two or more races.

20.6% of all households were made up of individuals, and 7.7% had someone living alone who was 65 years of age or older.