The Appalachian Trail or simply the A.T., is a marked hiking trail in the Eastern United States extending between Springer Mountain in Georgia and Mount Katahdin in Maine. The trail is about 2,200 miles (3,500 km) long, though the exact length changes over time as parts are rerouted or modified. The Appalachian Trail Conservancy describes the Appalachian Trail as 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.