J Thoendell stashed this in Maps
Scientists estimate that in about 10 years, America will have only three dark patches of land where people will be able to clearly see the Milky Way and where they'll be able to do high-quality astronomy and nocturnal wilderness research.
Those areas are southeastern Oregon and western Idaho; northeastern Nevada and western Utah; and northern Arizona and southeastern Utah — the better part of the Colorado Plateau.
The light-sprawls of the greater Las Vegas and Phoenix areas imperil dark skies in both the Colorado Plateau and northeastern Nevada and western Utah. The Oregon-Idaho patch is not near large cities.