I tried a google search to find relos on the AT, hoping to find details of the more significant changes in the route over the decade like the on in Virginia (1950s), Cumberland Gap (PA) and so on. What I found are the numerous ones more recently. Here are the links.
https://virginiasmtnplayground.com/relocated-section-of-the-appalachian-trail-will-officially-open/
https://ktalehighgapat.weebly.com/news/planned-relocations-on-ktas-section-ofthe-appalachian-trail
https://www.satc-hike.org/at-relocation-2022.html
https://www.fs.usda.gov/project/?project=59211
https://m.facebook.com/events/284296643109318/?source=3&action_history=null
https://smokymountainnews.com/archives/item/32652-a-t-gets-1-2-miles-longer
https://www.nynjtc.org/news/appalachian-trail-rerouted-west-mountain-harriman-state-park
https://www.youtube.com/watch?v=_N8htcfyJoo
https://www.fs.usda.gov/project/?project=59209
and some news clips
https://www.baltimoresun.com/news/bs-xpm-1992-12-27-1992362042-story.html
https://www.latimes.com/archives/la-xpm-1985-02-24-mn-24470-story.html
This is why the official length of the AT continues to grow (or shrink).
In the meantime, here are some photos of a relo in Massachusetts, some 200 feet I believe, to avoid a wet spot.
Thanks to the thousands of AT Volunteers!
And if interested a paper on volunteers.