Hello.
The Appalachian Trail (Q620648) is 2,198.4 miles (3,538 km) long. Here is an official source: https://appalachiantrail.org/news/appalachian-trail-2023-length/
I updated the length value, by putting the actual and correct certified length, including the metric equivalent, and added this official source as reference.
Yours sincerely, Multituberculata (talk) 20:49, 25 November 2023 (UTC)