http://www.elcaminodelavaca.org

Russell Corfman posted the route:

The Black Canyon National Recreation Trail, or BCT, is a ~75 mile trail running North to South from the Prescott National Forest Boundary to the Carefree Highway. The trail is a multi-use pathway for hikers, cyclists, and equestrians. The trail follows ancient Indian pathways, Sheep herding migration paths, and stage coach routes. The trail was designated as a National Recreation Trail in 2008. There are two loops along the trail, so travelling end to end is about 75 miles.

This is a 30 mile loop in Big Bend National Park.

https://www.nps.gov/bibe/planyourvisit/bc_outermountainloop.htm

Difficulty: Strenuous; significant elevation changes and primitive trail
Distance: 30 miles (side-trips to the South Rim or Emory peak add up to five additional miles).
Time: Allow at least three days