Arco is a city in Butte County, Idaho, United States.

Arco was the first community in the world ever to be lit by electricity generated solely by nuclear power.

[8] NRTS made further history on January 3, 1961, when the SL-1 reactor was destroyed through an operator maintenance error, with the ensuing steam explosion causing the deaths of all three personnel present.

[9] The town's economic base is primarily derived from the Idaho National Laboratory (formerly the Idaho National Engineering Laboratory or INEL), agricultural products, and recreation in the Lost River Valley.

Craters of the Moon National Monument is located along U.S. Route 20, southwest of the city.

Butte County High School has a tradition of each class since 1920 painting its graduation year on the face of hill.

[12] As of the 2010 United States Census[3] of 2010, there were 995 people, 417 households, and 254 families living in the city.

As of the 2000 United States Census[16] of 2000, there were 1,026 people, 427 households, and 269 families living in the city.