ALSO! While we're in the luxurious Front Royal library, thought it'd be fitting to send some references your way. Here are some good sites, in case you care to look a little closer at the Appalachian Trail...
Interactive map (via Google) on ATC site
This site calculates exact distances...we started at US 33 / Swift Run Gap in Virginia
Appalachian Trail Conservancy - group that manages the overall care of the trail - specifically, this is their FAQ page