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Mackinac National ParkArch Rock is one of the outstanding sights in America's second national park, Mackinac, established in 1875, not long after Yellowstone National Park. Never heard of Mackinac? While Yellowstone remains one of the U.S. National Park Service's crown jewels, Mackinac was abolished after only 20 years—making it one of 26 sites that geographer Bob Janiskee calls "pruned" national parks."Six percent of all the national parks that have ever been created have been dropped," said Janiskee, now retired from the University of South Carolina. "During the sixties, seventies, and eighties, there was a period of tremendous growth, but it gets lost in the shuffle that parks also get abolished or decommissioned."Janiskee frequently writes about the parks for National Parks Traveler, where he has profiled each of the 26 "gone and mostly forgotten" parks like Mackinac, which was transferred to the state of Michigan and is today protected as Mackinac Island State Park.–Brian Handwerk

Photograph by Ed Wargin, Corbis