The trail is estimated around 2,200 miles (3,500 km) long, though the exact length changes over time as parts are modified or rerouted. The Appalachian Trail Conservancy reports that the Appalachian Trail is the longest hiking-only trail in the world. More than 2 million people are said to take a hike on part of the trail at least once each year.
The idea of the Appalachian Trail came about in 1921. The trail itself was completed in 1937 after more than a decade of work, although improvements and changes continue. It is maintained by 31 trail clubs and multiple partnerships, and managed by the National Park Service, United States Forest Service, and the nonprofit Appalachian Trail Conservancy.
Most of the trail is in forest or wild lands, although some portions traverse towns, roads and farms. It passes through 14 states: Georgia, North Carolina, Tennessee, Virginia, West Virginia, Maryland, Pennsylvania, New Jersey, New York, Connecticut, Massachusetts, Vermont, New Hampshire, and Maine.