Washington County is a county in Idaho, United States, about 60 miles northwest of Boise along
the Snake River. It had a population of 10,500 at the 2020 census, an estimated 11,583 by 2025,
and covers 1,474 square miles (3,820 km2) centred near 44°27′N 116°47′W.
Weiser is the county seat and largest city; its postal code is 83672. The county holds 1 city,
2 incorporated towns and 11 smaller unincorporated communities, and it runs on Mountain Time.
Its FIPS code is 16087.
Towns & Villages in Washington County
Washington County has 14 named places on record: 3 incorporated cities and towns and 11
unincorporated communities with no local government of their own. Unincorp. covers crossroads,
former mining camps and rural place names with no formal boundary.
| Place | Type | Pop. | ZIP |
|---|---|---|---|
| Weiser | City · seat | 5,630 | 83672 |
| Cambridge | Town | 335 | 83610 |
| Midvale | Town | 193 | 83645 |
| Salubria | Unincorp. | — | — |
| Crystal | Unincorp. | — | — |
| Barton | Unincorp. | — | — |
| Concrete | Unincorp. | — | — |
| Diamond | Unincorp. | — | — |
| Eaton | Unincorp. | — | — |
| Feltham | Unincorp. | — | — |
| Heath | Unincorp. | — | — |
| Jonathan | Unincorp. | — | — |
| Mineral | Unincorp. | — | — |
| Rebecca | Unincorp. | — | — |
Salubria sits just east of Cambridge on the old Cambridge-to-Council road and predates it —
Cambridge grew up around the rail depot after the Idaho Northern line bypassed Salubria in 1901,
and most of Salubria’s businesses eventually relocated to the new town. The other ten
communities on this list are GNIS-recorded place names for former mining camps, ranches and rural
crossroads scattered through the Seven Devils foothills and the Weiser River valley; none carries
its own municipal government, post office or census count today.
ZIP Codes
- 83672 — Weiser (also covers the surrounding rural routes)
- 83610 — Cambridge
- 83645 — Midvale
Salubria, Crystal, Barton, Concrete, Diamond, Eaton, Feltham, Heath, Jonathan, Mineral and
Rebecca have no ZIP code of their own; mail to those places is delivered under whichever of the
three incorporated towns lies nearest.
Geography
Washington County sits in west-central Idaho, on the Snake River’s eastern bank where it
forms the Oregon border. Of the county’s 1,474 square miles, 1,453 are land and 21 are water,
about 1.4 percent, held mostly in reservoirs rather than natural lakes — Brownlee Reservoir
on the Snake, plus Crane Creek, Mann Creek and Paddock Valley reservoirs. The Weiser River runs
the length of the county from north to south before joining the Snake at the city of Weiser, and
the Seven Devils foothills rise along the county’s eastern edge toward Adams County.
Adams County borders Washington County to the north, Gem County to the east, Payette County to
the south, and Malheur County, Oregon, lies across the Snake River to the west. Adams County, Gem County, Payette County and Malheur County all border Washington
directly.
Demographics
Washington County had a population of 10,500 at the 2020 census, and a 2025 estimate puts the
county near 11,583 residents, a gain of roughly 10 percent. Weiser holds more than half the
county’s population outright, with Cambridge a distant second and Midvale third. Median
household income runs about $54,000, below Idaho’s statewide 2023 ACS figure of $74,942.
Population density works out to roughly 7 people per square mile of land, low even by rural Idaho
standards, and just over half the county’s residents live in Weiser’s urbanized area
while the rest are spread across the Weiser River valley and the surrounding ranch country.
Economy & Local Life
Manufacturing is the county’s largest employment sector, with about 485 workers, followed
by educational services at 467 and construction at 445. Weiser Memorial Hospital and the local
school district are among the county’s biggest single employers, and farm, orchard and
livestock operations still anchor much of the rural economy along the Weiser and Snake river
bottoms. The county’s best-known annual event is the National Oldtime Fiddlers’
Contest, held in Weiser during the third full week of June every year since 1953; it draws more
than 7,000 visitors and has earned the city its nickname, the Fiddling Capital of the World.
History
Idaho’s territorial legislature created Washington County on 20 February 1879, naming it
for President George Washington. Weiser, at the confluence of the Weiser and Snake rivers, became
the county seat as the area’s farm and orchard economy grew around the rail line. Cambridge
took shape after the Idaho Northern Railway reached the valley in 1901 and bypassed the older
settlement of Salubria nearby, drawing most of Salubria’s businesses to the new depot town.
Weiser also has a niche place in baseball history: Hall of Fame pitcher Walter Johnson played
semi-pro ball for the Weiser Kids in 1906 and 1907, at age 19, before signing with the Washington
Senators and going on to a 21-season major league career.
Getting There
No interstate crosses Washington County. U.S. Route 95 runs the length of the county
north–south through Weiser, Cambridge and Midvale, and State Highway 71 branches northwest
from Cambridge toward Brownlee Dam on the Snake River.
- Boise — about 60 miles south
- Ontario, Oregon — about 20 miles west
- Payette — about 14 miles south
- McCall — about 88 miles north
Boise Airport, roughly 60 miles south of Weiser, is the nearest scheduled commercial air
service. The county has no Amtrak service; Idaho currently has no active Amtrak routes at all.
Frequently Asked Questions
Where is Washington County located?
It sits in west-central Idaho along the Snake River, about 60 miles northwest of Boise, bordered
by Adams, Gem, Payette and Malheur (Oregon) counties.
What is the population of Washington County?
10,500 at the 2020 census, with a 2025 estimate near 11,583.
How big is Washington County?
1,474 square miles (3,820 km2), of which 1,453 square miles are land.
What is the county seat of Washington County?
Weiser, at the confluence of the Weiser and Snake rivers, is the county seat and largest city.
How many towns and cities are in Washington County?
Three incorporated places — Weiser, Cambridge and Midvale — plus eleven
unincorporated communities: Salubria, Crystal, Barton, Concrete, Diamond, Eaton, Feltham, Heath,
Jonathan, Mineral and Rebecca.
What ZIP codes does Washington County use?
83672 for Weiser, 83610 for Cambridge and 83645 for Midvale.
What is Washington County known for?
The National Oldtime Fiddlers’ Contest, held in Weiser every June since 1953, and Weiser’s
brief place in baseball history as Walter Johnson’s semi-pro proving ground.
More counties in this state: Towns and villages in Idaho.