Hailey, ID. Sponsored Topics. Hailey is a city in and the county seat of Blaine County, in the Wood River Valley of the central part of the U.S. state of Idaho. The population was 6,200 at the 2000 census. Hailey is the site of Friedman Memorial Airport (SUN), the airport for the resort area of Sun Valley/Ketchum, 12 miles (19 km) north.