In 1922, the Southern Appalachian National Park Commission proposed a new national park in Kentucky, inspired by the Green River, the forested hills, and the cave beneath them. Charged with finding new parklands, the commission judged the “great underground labyrinth,” the apparently original forest, and the beautiful and navigable Green River and its branch the Nolin River worthy to rank with treasures such as Shenandoah and the Great Smoky Mountains. Through the efforts of the state legislature, the Mammoth Cave National Park Association, and countless local citizens, parcels of land were acquired for Mammoth Cave National Park, established in 1941. Today the park comprises 52,830 acres, with more than 70 miles of hiking trails providing access to a range of forest communities containing some 84 species of tree and more than 1,000 species of flowering plants. The Green River has one of the most diverse fish and mussel populations in North America, and the park was recognized as a World Heritage Site on October 27, 1983, and a Biosphere Reserve on February 7, 1990.