Some interesting facts: (via appalachiantrials.com)
- the elevation gain/loss while hiking the AT is nearly the same as hiking up and down Mt. Everest from sea-level 16 times.
- you cross some type of road on average of every 4 miles.
- the highest point on the entire trail is on top of Clingmans Dome, in the Great Smoky Mountains in Eastern Tennessee, and maxes out at the elevation of 6644.
- the trail cuts through what is arguably the oldest mountain range on the planet, predating even the creation of the now North America Continent.