Forest County is the smallest county in Pennsylvania, both in size and composition.
It's name comes from the unbroken wilderness of trees that covered the area, which heavily dominates even today. It contains 420 square miles of land, most of which is still wooded. To conserve virgin pine and hemlock, Cooke State Forest was formed in 1970, and 3,181 acres of it are located in Forest county. Allegheny National Forest covers many acres in the county as well. The Allegheny River's many tributaries, principally Hickory and Tionesta Creeks, were important for transporting lumber and iron ore to market in Pittsburgh and other cities along the Mississippi.