Arco, ID

Arco sits along US Highway 20 in south-central Idaho's high desert, serving as Butte County's seat at over 5,300 feet elevation. The town connects Idaho Falls (65 miles southeast) with Sun Valley and Craters of the Moon National Monument to the northwest. Most visitors pass through on long-distance routes between Yellowstone and Sun Valley, while locals use Highway 22 north to Mackay. Arco was the first city worldwide powered entirely by nuclear energy, achieved for one hour in 1955.