Contrary to the name, Twentymile Trail extends only 5 miles into the backcountry of the Great Smoky Mountains National Park. A 20-mile trip can be made by linking to other trails around it or by just continuing along the Benton MacKaye Trail, which Twentymile trail is a section of.
Starting from the Twentymile Ranger Station, the trail goes 0.5 miles in before seeing the Wolf Ridge Trail branch off to the left. After this, the trail goes 2.6 miles through Campsite #93 and to the trail junction meeting of Twentymile Loop Trail and Long Hungry Ridge Trail. Continuing on, Twentymile Trail runs 1.9 miles to where it ends at the intersection of the Appalachian Trail near Shuckstack. After this, the Twentymile Trail section of Benton MacKaye Trail becomes the Lost Cove Trail.