Conservancy: Appalachian Trail grows by 1.9 miles - Asheville Citizen-Times

[WhiteBlaze]

Conservancy: Appalachian Trail grows by 1.9 miles Asheville Citizen-Times Relocations and remeasurements of the Appalachian Trail now put it at 2181 miles, 1.9 miles longer than previous estimates. The new official length of the ...

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[SassyWindsor]

I would say the AT mileage has changed every year since its construction. The biggest change was probably when the southern terminus, Mt. Oglethorpe, was relocated to Springer, not sure of the mileage, but easy to look up.

[emerald]

http://en.wikipedia.org/wiki/Mount_Oglethorpe

In 1958, as a result of over development around Mount Oglethorpe, the southern terminus of the Appalachian Trail was moved about 20 miles (32 km) to the northeast to Springer Mountain.

Many longer relocations occurred.