Celebrate a century of the American Park Service by exploring the system's very best national parks, from arctic Denali to tropical Dry Tortugas. Congress created the National Park Service in 1916, though the first national park predated it by over forty years. (Wyoming did not yet exist when the federal government established Yellowstone in 1872, meaning it rather than a state government had to run the park.) The work of politicians and advocates such as John Muir, Ulysses S. Grant, and Theodore Roosevelt helped lay the ground for a truly astounding network of natural, national treasures, owned in part by every American citizen. The parks that regularly chart at the top for popularity are Grand Canyon, Rocky Mountain, Yosemite, Yellowstone, Zion, Olympic, Grand Teton, Acadia, and Glacier.