The National Park Service, a bureau of the Department of the Interior, is entrusted with administering approximately 84,000,000 acres of land throughout nearly 400 national park units in all 50 states, the District of Columbia, Puerto Rico, the U.S. Virgin Islands, and Guam. The mission of the National Park Service is to preserve unimpaired the natural and cultural resources and values of the national park system for the enjoyment, education, and inspiration of this and future generations. This is accomplished through a deeply committed workforce of approximately 17,000 employees (both permanent and temporary) and partnerships with nonprofit organizations, state and local governments, and private industries. Great Smoky Mountains National Park (GRSM) covers 522,427 acres, divided almost evenly between the states of North Carolina and Tennessee. Elevations in the park range from approximately 875 feet at the mouth of Abrams Creek to 6,643 feet at Clingmans Dome. The park has 10 frontcountry campgrounds, 11 picnic areas and more than 100 backcountry campsites including shelters. Approximately 850 miles of trails, including 70 miles of the Appalachian Trail run through the park. There are 384 miles of roads as well as 342 structures that are maintained in the park. GRSM has the highest visitation of any national park with approximately 12 million recreational visits, and it is one only a few national parks that does not charge an entrance fee. GRSM has approximately 190 permanent and more than 80 seasonal employees, as well as over 2,600 volunteers.