Twin Falls is the county seat and largest city of Twin Falls County, Idaho^GR6. As of the 2000 census Twin Falls population was 34,469 (2003 estimate: 36,742).

Twin Falls is the largest city of Idaho's Magic Valley region and the seventh largest in the state. As the largest city in a 100-mile (166-kilometer) radius, Twin Falls serves as a regional commercial center for both south-central Idaho and northeastern Nevada.

Twin Falls is the principal city of the Twin Falls, ID Micropolitan Statistical Area - the state's largest - which officially includes Jerome and Twin Falls Counties. The resort community of Jackpot, Nevada, in Elko County is unofficially considered part of the greater Twin Falls area.