Allegheny National Forest in northwestern Pennsylvania covers 513,175 acres on the Allegheny Plateau, where Kinzua Dam creates the Allegheny Reservoir. Established in 1923 after the Weeks Act enabled federal purchase of eastern forest lands, it arose from a landscape heavily cut between about 1890 and 1930 for logging, tanning, and wood-chemical production. As the land regrew, sun-loving hardwoods, especially black cherry, replaced much of the earlier hemlock-beech forest, and much of the area came to be managed through even-aged silviculture. The forest also protects notable old-growth remnants, supports research begun in 1923, and serves timber, watershed, wildlife, and recreation needs.