Leaders in the cities of Ketchum and Sun Valley, the tiny mountain town of Stanley, other local and federal officials, and a conservation group have been working for several years to apply this fall to designate 1,400 square miles (3,600 square kilometers) as a reserve. A final decision by the association would come about 10 weeks after the application is submitted.The association also designates International Dark Sky Parks, with nearly 40 in the U.S. Craters of the Moon National Monument and Preserve in central Idaho, known as a prime destination among avid stargazers, became one earlier this year.