Writer Wallace Stegner called our national parks "America's best idea." This idea--that areas of great natural, cultural, or historic significance should be preserved for the enjoyment and benefit of all--was still a novel one in 1872, when Yellowstone was established as the world's first national park. One-hundred and forty years later, there are 58 U.S. national parks. They are spread among 27 states and two U.S. territories, and cover 51.9 million acres. Their special status helps to ensure that they remain unspoiled for us and future generations.