Hartwick Pines State Park is a 3,951-ha public recreation area in Crawford County in Michigan's Lower Peninsula. The park includes an old-growth forest of white pines and red pines, commonly known as Hartwick Pines. The Hartwick Pines are the remnant of a 20-hectare old-growth pine forest that was taken out of logging by a local timbering company in 1927, as there were very few old-growth pines left in northern Michigan at that time. Karen Michelson Hartwick, the widow of lumberman Major Edward Hartwick, gifted the grove, which then covered 34 hectares, and the surrounding 32.4 km2 of cleared land to the State of Michigan in memory of the logging industry. In 1934-1935, the Civilian Conservation Corps built the Hartwick Pines Logging Museum. The museum features recreated exhibit rooms, photographs and artifacts from the logging boom years in northern Michigan. The site is housed in replicas of two logging camps and features outdoor exhibits of logging equipment, and an enclosed steam-powered sawmill which is operated during summer events. The Michigan Forest Visitor Center features an exhibit hall on the history of Michigan's forests, a lecture hall, classrooms, and a bookstore run by the non-profit Friends of Hartwick Pines. The state park features a campground, day use area and a four-season trail network for summer hiking and winter cross-country skiing. The Old Growth Forest Trail into the pine forest is a 2.0 km long loop. It is a stand of even-aged pine trees estimated to be between 350 and 375 years old.