Central Idaho Dark Sky Reserve, International Dark Sky Reserve in central Idaho, US

The Central Idaho Dark Sky Reserve is a protected area within the Sawtooth National Recreation Area in Idaho, where artificial lighting is kept to a minimum across a wide landscape of mountains and river valleys. The reserve covers a large portion of central Idaho and includes both public lands and several small towns that follow strict lighting rules.

In 2017, the International Dark-Sky Association gave this area its gold-tier designation, making it the first reserve of that level in the United States. That recognition came after years of work by local communities and land managers to reduce light pollution across the region.

Ketchum has had a dark-sky ordinance since 1999, and Sun Valley, also inside the reserve, has its own local lighting rules. The U.S. Forest Service, which manages much of the land, posts information signs about the reserve and has said it will cut light pollution from its buildings; for individuals on Forest Service land, compliance is voluntary.

Highway 75 runs through the reserve and gives access to several open areas well suited for watching the sky at night. Planning your visit around a new moon makes a noticeable difference in how dark the sky gets.

On very dark nights, zodiacal light becomes visible here, a faint glow caused by sunlight scattering off interplanetary dust along the plane of the solar system. This is something most people have never seen because light pollution erases it almost everywhere else.