Arco
- County:
- Butte County
- County Seat:
- Yes
- Area (mi²):
- 1.068
- State:
- Idaho
Arco is a city located in Butte County, Idaho. Arco has a 2026 population of 911. It is also the county seat of Butte County. Arco is currently declining at a rate of -1.19% annually but its population has increased by 3.64% since the most recent census, which recorded a population of 879 in 2020.