The usanp thread is here:
https://forum.travelmapping.net/index.php?topic=196.0I read the thread and found this comment. I think Chisos Basin Rd qualifies under #5
Criteria are:
1) a missing gap in an existing system (eg Mammoth Cave, California Routes, Yellowstone)
2) a specific NPS unit for the road (eg Natchez Trace, Blue Ridge, George Washington Memorial and Baltimore-Washington Parkways)
3) a through route linking roads already in (eg Painted Canyon Road)
4) an extension of an existing system into a park
5) roads that seem important enough and link with other roads - even if they dead-end
The Chisos Basin area is highlighted on the park map and is prominent on the park website. I believe the road to it merits inclusion.