Adam Wilcox posted the route:

The Grafton Notch Loop is 39 mile trail that was completed in 2007. Close to the Sunday River ski area in western Maine near the New Hampshire border, it generally follows the mountain ridge lines that surround Grafton Notch and the Bear River Valley, passing over the summits of Old Speck, the Baldpates, and Sunday River White Cap. From Old Speck to the East Baldpate the loops runs concurrently with the Appalachian Trail while the remainder is newly constructed trail with periodic campsites, shelters, and water sources available.

NOTE:  The Department of Conservation has asked hikers to stay off the Thunderbolt Trail in summer to prevent erosion!

https://www.facebook.com/271570818265/photos/a.10152512120138266.1073741828.271570818265/10156673789698266

Patrick Begley:

https://en.wikipedia.org/wiki/Taconic_Crest_Trail

The Taconic Loop is a recently-estalished route that consists of the entirety of the South Taconic Trail & a section of the AT between Jug End Rd(MA) & Undermountain Rd(CT). Current estimates put the length of the route at 45+miles & the vertical gain close to 8000'. Road connectors link the two trail segments & make up ~20% of the route:

South: osm.org/go/Zc~Pulq
North: osm.org/go/Zc~1MZX

This route has had some variations & discussion of the best combination of trails.  We preserve the discussion from our old website here.  The FKT progression is also documented.

Tim B (6/30/2016):

The Tri-State U (MA, CT, NY) is a non-established name for a route that goes thru Mass, CT, and NY. It crosses over 8 peaks in three states including the highest peak and point (not the same) in CT.

The Franconia Ridge Loop is a popular, 8+ mile route in the White Mountain National Forest of New Hampshire. It is accessed from Franconia Notch Parkway near the Lafayette Campground. The route goes by the Greenleaf Hut and summits Mt Lafayette (5240'), Mt Lincoln (5089') and Little Haystack (4780') on Franconia Ridge, see map below from sectionhiker.com.