Sun Valley is a resort city in Blaine County in central Idaho, in the western United States. The resort is adjacent to the city of Ketchum and within the greater Wood River valley. The population was 1,406 at the 2010 census, down from 1,427 in 2000.[4] The elevation of Sun Valley (at the Lodge) is 5,920 feet (1,805 m) above sea level. The area is served by Friedman Memorial Airport in Hailey, approximately 15 miles (25 km) south. Visitors to Sun Valley are relatively close to the Sawtooth National Recreation Area, accessed over Galena Summit on Highway 75, the Sawtooth Scenic Byway.

Among skiers, the term "Sun Valley" refers to the alpine ski area, which consists of Bald Mountain, the main ski mountain adjacent to Ketchum, and Dollar Mountain, adjacent to Sun Valley, for novice and lower intermediate skiers. Bald Mountain, or "Baldy," has a summit of 9,150 feet (2,790 m) and a vertical drop of 3,400 feet (1,035 m). With its abundance of constant-pitch terrain, at varying degrees of difficulty, coupled with its substantial vertical drop and absence of wind, Baldy has often been referred to as one of the better ski mountains in the world. The treeless "Dollar" at 6,638 feet (2,023 m) has a moderate vertical drop of 628 feet (191 m).

The term "Sun Valley" is used more generally to speak of the region surrounding the city, including the neighboring city of Ketchum and the Wood River Valley area winding south to Hailey and Bellevue. The region has been a seasonal home to the rich and famous since first being brought to public attention by Ernest Hemingway in the late 1930s.