The Appalachian Trail (AT) is a 2160 mile trail from Mount Katahdin, Maine to Springer Mountain, Georgia. It was conceived more than 75 years ago by Benton MacKaye. Only about 1% of the trail runs through "unprotected" areas. The AT is marked along the way by 2"x6" white blazes or mountaintop cairns. There are 3 sided shelters built every 10 miles or so.
The AT is also extremely well known to the local people and getting rides off-trail is much easier. There are several "trail angels". These are kindly folks who help out along the trail by offering soft drinks, water, food and assistance. It is also called "trail magic". Some of the trail angels have become quite legendary.
Every year about 3000 people attempt to thru-hike the AT of which about 10% succeed. About 80% are males. It draws from an exceptionally wide range of professions, a wide range of age groups (somewhat under represented by the 30 to 40 age group), but a narrow racial mix (very predominantly white). There is good camaraderie along the trail (especially north-bound) and it is not uncommon to make life long friends during a thru-hike.
Extensions are now being added to the AT and the whole thing is called Eastern Continental Trail. The north side has the International Appalactian Trail (IAT) that runs from Mount Katahdin, Maine to Park Forillion, Quebec, Canada for a distance of about 700 miles. The south is being extended from Springer Mountain, Georgia to Key West, Florida by the Benton MacKaye (100 miles), Georgia Pinhoti (150 miles), Alabama Pinhoti (150 miles) and Florida National Scenic Trail (1000 miles). There is also a significant roadwalk from the Alabama Pinhoti trail to the Florida National Scenic Trail (150 miles) ane form the Florida National Scenic Trail to Key West (150 miles). The entire trail is approximately 4700 miles. The extensions are relatively recent concepts and are not as developed as the AT. Some sections run along roads and most have no shelters. This is the more adventorous portion of the hike. There are also almost no hikers on the non-AT trails. I averaged on average 1 hiker every 7 days or so here.
ECT Trail Map
The AT has shelters every 10 miles or so. So one can plan the day\'s hike to end at a shelter and then sleep there. It also passes near a town about every 5 days. So hikers usually get their food and supplies during town stops. In some instances the trail runs through the town. More commonly, the hiker will either have to walk or hitchhike a little to get to the stores. One can thus think of a multi-month thru-hike as a series of 5 day hikes.
The non-AT trails are much younger and thus do not have the shelters or adequate maps or information. (The AT is often criticized for being over documented thus reducing the element of adventure). The trials are not well known, thus getting rides become more difficult. Here you are on your own.