backpacker.com decribes this 18-mile route in the Sawtooth National Recreation Area. "You might think you're in Yosemite except of the lack of crowds."

Will Porter posted the route with some great details:

Fastest ascents to either the top of the iconic Y above BYU campus in Provo, Utah, or to the top of Y Mountain itself, using the established Y Mountain Trail - people need to be clear exactly which their time refers to.  To the summit via the Y Mountain Trail has a Strava segment.

Learn more about the Y from BYU Magazine's article "An Ode to the Y."

The Flagstaff Loop Trail seems to be still in process, but there appears to be enough on the ground for people to begin reporting FKTs. ~45 miles

The Teton Crest Trail runs from the Phillips Pass trailhead on Teton Pass to String Lake via Paintbrush Canyon, about 38 miles.

Someone posting as "Scotsman" said:  "I have spoken to Trevor Garner who has an unrecorded time of 8hrs. 10 minutes."

Then "TDOG" posted:

Marcy Beard posted the idea:

Hello!  I'm planning a long run starting tonight from the Alamo in San Antonio to the Capitol building in Austin.  It will be self-supported, using stores/restaurants along the way.  My route will for the most part follow I-35 or parallel to it.  Remains to be seen just how challenging it will be to run along the access road.