Death Valley is famous for being extremely hot during the summer, but that harsh climate gives it an advantage -- city dwellers don't want to be anywhere near the place. This means that many of its skies are practically free of artificial light. However, as cities such as Las Vegas continue to grow, its status as a "gold" (highest tier) dark-sky park could come under threat. The IDA said that brighter skies could also affect the local wildlife.
"Much of the night sky above the desert floor is near pristine and, in many places, offers views close to what could be seen before the rise of cities," the IDA wrote on its website.
3) Great Basin National Park (Nevada)