Valley County is a rural county located in the U.S. state of Idaho. As of the 2020 census, the population was 11,746. The county seat is Cascade, and the largest city is McCall. Established in 1917, it was named after the Long Valley of the North Fork of the Payette River, which extends over 30 miles (50 km) from Payette Lake at McCall south to Cascade to Round Valley. The valley was formerly a summer pasture for livestock from the Boise Valley. Since the completion of the Cascade Dam in 1948, much of the northern valley has been covered by the Cascade Reservoir.

Cascade is a rural city in and the county seat of Valley County, Idaho, United States. The population was 939 at the 2010 census, down from 997 in 2000.