Butte County is a county in Idaho, United States, in the upper Snake River Plain south of Craters of the Moon National Monument. It had a population of 2,574 at the 2020 census and covers 2,234 square miles (5,790 km2) centred near 43°43′N 113°10′W.
Arco is the county seat, and its postal code is 83213. The county has three incorporated cities, three named unincorporated communities and a scatter of historic rangeland settlements. All of Butte County runs on Mountain Time, and it is entirely rural — the U.S. Census Bureau classifies none of its population as urban.
Towns & Villages in Butte County
Butte County has three incorporated cities — Arco, Butte City and Moore — plus a handful of unincorporated communities and rangeland place-names carried in the county’s historical record. Idaho has no civil townships, so places are not grouped by township below. CDP = census-designated place; Unincorp. = unincorporated community with no municipal government.
| Place | Type | Pop. | ZIP |
|---|---|---|---|
| Arco | City · seat | 879 | 83213 |
| Moore | City | — | 83255 |
| Butte City | City | — | 83213 |
| Howe | Unincorp. | — | 83244 |
| Darlington | Unincorp. | — | 83213 |
| Lost River | Unincorp. | — | 83213 |
| Clyde | Unincorp. | — | 83213 |
| Era | Unincorp. | — | 83213 |
| Berenice | Unincorp. | — | 83213 |
| Martin | Unincorp. | — | 83213 |
| Scoville | Unincorp. | — | 83213 |
| Smith Corrals | Unincorp. | — | 83213 |
Clyde sits in the county’s Clyde area, land Custer County ceded to Butte County in 1937; several of the smaller rangeland names above (Berenice, Era, Martin, Scoville, Smith Corrals) mark old sheep-and-cattle stage stops and homestead sidings along the Big Lost River rather than active settlements, and none carries its own census count.
ZIP Codes
- 83213 — Arco (also serves Butte City, Darlington, Lost River, Clyde, Era, Berenice, Martin, Scoville and Smith Corrals)
- 83255 — Moore
- 83244 — Howe
Most of the county’s unincorporated places have no post office of their own and are served by the Arco ZIP.
Geography
Butte County lies on the Snake River Plain in central Idaho, a landscape dominated by three volcanic buttes — Big Southern Butte, East Butte and Middle Butte — that gave the county its name. The county’s western reach climbs into the Lost River Range, and Craters of the Moon National Monument covers part of its southwestern corner. A large share of the county’s north lies inside the federal Idaho National Laboratory reservation, closed to the public. The Big Lost River, which sinks into the desert sand rather than reaching any ocean, is the county’s principal watercourse.
Butte County borders Custer County to the northwest, Lemhi County to the northwest, Clark County to the northeast, Jefferson County to the east, Bingham County to the southeast and Blaine County to the southwest.
Demographics
Butte County had 2,574 residents at the 2020 census, giving it a density of about 1.2 people per square mile — one of the lowest in Idaho. Arco and Moore are the county’s two largest communities. Median household income runs well below the Idaho median of $74,942; Butte County’s economy is dominated by lower-wage ranching, farm-labor and public-sector jobs rather than the state’s growing tech and services sectors.
Economy & Local Life
Irrigated hay, barley and potato farming along the Big Lost River, cattle and sheep grazing on the surrounding range, and government employment at the nearby Idaho National Laboratory anchor the county’s economy. Arco holds a place in nuclear history: on July 17, 1955, it became the first town in the world lit by nuclear-generated electricity, powered by an experimental reactor at the laboratory site, and the town still marks the anniversary each summer.
History
Butte County was organized on February 6, 1917, from portions of Bingham, Blaine and Jefferson counties, and took its name from the three prominent Snake River Plain buttes that guided fur trappers and pioneer travelers across the surrounding desert. In 1937, Custer County transferred the Clyde area to Butte County, fixing the county’s present boundary. Arco, the county seat, had already been platted decades earlier as a stage and rail stop before the county itself existed.
Getting There
U.S. Routes 20, 26 and 93 and Idaho State Highways 22 and 33 cross the county, meeting at Arco.
- Idaho Falls — 72 miles east
- Pocatello — 75 miles southeast
- Twin Falls — 105 miles southwest
- Sun Valley/Ketchum — 60 miles southwest
The nearest commercial airport is Idaho Falls Regional Airport.
Frequently Asked Questions
Where is Butte County?
It is in central Idaho, on the Snake River Plain south of Craters of the Moon National Monument.
What is the population of Butte County?
2,574 people, at the 2020 census.
How big is Butte County?
2,234 square miles (5,790 km2), most of it rangeland and desert.
What is the county seat of Butte County?
Arco, also the county’s largest city.
How many towns and communities are in Butte County?
Three incorporated cities — Arco, Butte City and Moore — plus several smaller unincorporated communities including Howe, Darlington and Lost River.
What ZIP codes are in Butte County?
83213 (Arco), 83255 (Moore) and 83244 (Howe).
Why is Arco historically significant?
In 1955 it became the first town in the world powered by nuclear-generated electricity, from a test reactor at the nearby Idaho National Laboratory.
More counties in this state: Towns and villages in Idaho.