Keystone State Park is a 1,200-acre (486 ha) Pennsylvania state park in Derry Township, Westmoreland County, Pennsylvania in the United States. The main attraction of the park, which opened in 1945, is the 78-acre (32 ha) Keystone Lake, constructed by the Keystone Coal and Coke Company in the early 1900s. The park also has extensive picnic areas and several miles of hiking trails. Keystone State Park was named after the Keystone Coal and Coke Company that once occupied the area. The park is off U.S. Route 22 near New Alexandria.