national park service was created, to protect america's natural wonders from development. pday, the park service oversees 413 sites, including 59 major national parks covering 84 million acres, from great smoky mountains-- the most visited-- to the grand canyon, the everglades, and the newest addition, katahdin woods and waters national monument in maine, designated by president obama just yesterday. mike reynolds is deputy director of the national park service: >> if you're a science person, you can go to edison and be in his lab, as if he had never dift. if you're a rock climber, you can hang upside down on yosemite national park on 4,000-foot iniffs. .f you're a history buff, you can walk through the steps of jackson and lee in the civil war. >> reporter: decades ago, some politicians wanted to turn this old towpath and canal in maryland into a highway. but nature lovers prevailed. today it's the c&o canal national historic park. it runs 185 miles, all the way