The first purchase of land for the William Penn State Forest was in January, 1935. The Commonwealth paid $1.00 to the Cornwall Estate for ten acres in Lancaster County near the Lebanon County line. The site contained the Cornwall fire tower which was erected in 1923.
It was almost 48 years before the next purchase. In November, 1982, Little Tinicum Island, 200 acres in the Delaware River, Delaware County, was acquired. The island was acquired to preserve its unique, to Pennsylvania, ecology.
The very next month, December, 1982, another unique ecological site was acquired. The Goat Hill Serpentine Barrens, 602 acres of the approximately 1,000 acre barrens, was purchased with the assistance of the Nature Conservancy.
In August, 2007, the forest district was named the William Penn State Forest. Formerly known as the Valley Forge State Forest, the state forest district was headquartered at what had been a state park at Valley Forge until 1976, when the facility became a federal park. The state forest kept the name for the next 31 years.
In a bid to eliminate public confusion over the name of the federal park and the state forest district, the Bureau of Forestry renamed the Valley Forge State Forest District in honor of one of Pennsylvania's first conservationists -- William Penn.
In 2015, an era of expansion began for the William Penn State Forest. Partnering with local conservation agencies, new tracts of land were added to the forest, totaling 634 acres that year.
The Buck Hollow Tract (80 acres) was added in 2016, followed by a 45 acre parcel close to the Wertz Tract in 2017. These new lands enable the William Penn to further DCNR’s Bureau of Forestry’s mission and provide recreational opportunities to the public.