Thirteen is the shortest (northern). The other two (southern) are 20 & 30 miles. The maintenance has apparently gotten worse since then. Their description of the southern routes is now "Both routes can vary from very rough to impassable."

I don't have a problem with protecting sites with isolation. Isolating the entire park including visitor's center is another matter. I can easily see isolating parts of Chaco Canyon, especially the petroglyphs. I can see some joker deciding to add to them if they didn't.