The 8,200-acre Cook Forest includes one of the largest stands of old-growth white pine in eastern North America. The commonwealth's acquisition of the hemlock and pine forest in 1927 was the first time Pennsylvania acquired land specifically to preserve a natural resource, and it signaled a growing awareness of recreational lands as an economic generator.
John Cook came to the area in 1826 in search of a route for an east–west canal. He did not succeed in that mission, but did purchase the surrounding forest land c. 1828. He built a successful lumbering operation and his large family continued the business through the nineteenth and early twentieth centuries. In the 1920s, one of John Cook's descendants, Anthony Wayne Cook, began to urge his fellow heirs to preserve the 3,000 uncut acres that surrounded the family home. The family sacrificed much of their fortune to pay taxes on the undeveloped land in a conscious effort to preserve the mature forest of 200- to 300-year-old hemlock and pine trees with a 200-foot canopy.
Several important buildings are situated in the park, including Cook's Homestead (1868–1870), now a white frame bed-and-breakfast. The two-story structure has little ornamentation other than a porch along two elevations. It was once home to Anthony Cook and his family of five children. Soon after the commonwealth's purchase of the forest lands, the CCC built cabins and stone and wood shelters for recreational purposes. The largest of these, the Log Cabin Inn, was constructed in 1934. A preserved sawmill houses an exhibit on forestry. The irregular shape of the park reflects the gradual and piecemeal accumulation of lands by the state, which continues to purchase lands for inclusion in the park. Two private homes surrounded by parklands remain in the Cook family.