Power County is a county located in the U.S. state of Idaho. As of the 2020 Census, the county had a population of 7,878. The county seat and largest city is American Falls. The county was created by the Idaho Legislature on January 30, 1913, by a partition of Cassia County. It is named for an early hydroelectric power plant (1902) at the American Falls.

Cassia County is a county in the U.S. state of Idaho. As of the 2020 Census the county had a population of 24,655. The county seat and largest city is Burley. Cassia County is included in the Burley, ID Micropolitan Statistical Area.