Trans-America Trail" This was the brainchild of Sam Correro, who thought it would be a great adventure to go cross country using as little pavement as possible on dual-sport motorcycles.
The trail is set up to be navigated from East to West and there are "roll charts" already set up for purchase of the entire route. Much like the Great Divide Trail, there are sections where the trail runs on paved road, but for the most part, this is gravel and worse across the U.S.A. from Tennessee to Oregon. The route was conceptualized to start at the East Coast, but for now is approximately 4800 miles as is.
There is also a north-south route and an out and back loop in Mississippi listed on the site.
Checking out the info available on the site,I only see that some of the water crossings might be an issue for adventurous cyclists, but if you think you can do the Tour Divide, then this could be the ultimate next step on bicycles. Self supported, a full length, coast to coast "Trans-America By Bicycle" could eventually be nearly twice as long as Tour Divide. Think of the adventures that would entail!
Even if doing a straight through race on this trail doesn't sound appealing, the route may provide the basis for more "trans-type" cycling events like Trans Wisconsin, which itself grew out of a motorized adventure route.