Sun Valley is a resort city in the western United States, in Blaine County, Idaho, adjacent to the city of Ketchum in the Wood River valley. The population was 1406 at the 2010 census, down from 1427 in 2000. The elevation of Sun Valley (at the Lodge) is above sea level.
Among skiers, the term "Sun Valley" refers to the alpine ski area, which consists of Bald Mountain, the main ski mountain adjacent to Ketchum. Dollar Mountain, which is adjacent to Sun Valley, is suited for novice and lower intermediate skiers. Bald Mountain, or "Baldy," has a summit of and a vertical drop of . The treeless "Dollar" at has a moderate vertical drop of .
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.