The Appalachian Trail is approximately 2,190 miles long, the trail traverses 14 different states. There is an approximate gain/loss in elevation of 464,500 Feet. The Appalachian Trail is one of the most well-known trails in the country. Known as the A.T. to those who forge the path, it runs for more than 71 miles through Great Smoky Mountains National Park. Hikers follow the Appalachian Trail with the assistance of a system of “blazes” painted on trees, posts and rocks.