Arco was the first city in the world to be lit by Atomic power, July 17, 1955. It is also the gateway city to Craters of the Moon National Monument. Arco is the largest city and county seat in Butte County, Idaho, United States. The population was 995 at the 2010 census. Arco is located along the Big Lost River near the Snake River Plain.
Arco is home to the Idaho Science Center and home base for many outdoor recreation opportunities.