The trail shall include public roads linking El Malpais National Monument as established pursuant to part A of this subchapter, El Morro National Monument, Chaco Cultural National Historical Park, Aztec Ruins National Monument, Canyon De Chelly National Monument, Pecos National Monument, Gila Cliff Dwellings National Monument, Zuni-Cibola National Historical Park, and Petroglyph National Monument. The Secretary may, in the manner set forth in section 460uu-11 of this title, designate additional segments of the trail from time to time as appropriate to link the foregoing sites with other cultural sites or sites of national significance when such sites are designated and protected by Federal, State, or local governments, Indian tribes, or nonprofit entities.