BC
Boise County
Idaho · Est. February 4, 1864
◌ —°F Idaho City
Idaho City →
Idaho · Boise County · Est. 1864

Boise
County

State of Idaho · Boise County, ID · County Seat: Idaho City

One thousand nine hundred and seven square miles of mountain wilderness, gold rush legacy, and some of the finest whitewater in the American West. From the Ponderosa Pine Scenic Byway to the peaks of the Sawtooth, this is where Idaho's story began.

1864
Year Founded
1,907mi²
Total Area
76%
Federal Land
10,751
Highest Ft — Thompson Peak
8.5K
Population (2026 est.)
◈ Explore the County Idaho City — County Seat →
44°01′N
Latitude
115°44′W
Longitude
3,944ft
Idaho City Elev.
40mi
From Boise
Hwy 21
Ponderosa Pine Byway
Hwy 55
Payette River Byway
The County

A Mountain County at the Heart of Idaho

Boise County is a rural mountain county in the U.S. state of Idaho, established by the Idaho Territorial Legislature on February 4, 1864. Named for the Boise River — itself named by French-Canadian trappers for the forested banks along its lower course — the county encompasses 1,907 square miles of Idaho's central mountain terrain.

The county seat is historic Idaho City, 40 miles northeast of Boise on State Highway 21 (Ponderosa Pine Scenic Byway). At its mid-1860s peak, Idaho City was the largest city in the entire Pacific Northwest — larger than Portland, Seattle, or San Francisco — built on the staggering wealth of the Boise Basin gold rush.

Today, Boise County is part of the Boise Metropolitan Statistical Area. With approximately 8,584 residents (2026 est.) spread across 1,907 square miles, it remains one of Idaho's most sparsely populated counties — 3.7 people per square mile — a statistic that tells the story of immense public land, mountain terrain, and enduring remoteness.

Official county government is headquartered at 420 Main Street, Idaho City, ID 83631. Phone: 208-392-4431. Website: boisecounty.us
County Seat — Idaho City
419 Main Street, Idaho City, ID 83631. idahocity.org · Once the largest city in the Pacific Northwest.
Largest City — Horseshoe Bend
Located on the Payette River along State Highway 55. Former gold rush staging area, now a small-town gateway to Boise County.
76.4% Federal Land
The vast majority of Boise County lies within the Boise National Forest, BLM land, and the Sawtooth National Recreation Area. Only 16.5% is privately held.
Boise Metro MSA
Boise County is included in the Boise Metropolitan Statistical Area, a region approaching 900,000 residents and one of the fastest-growing in the American West.
Gold Rush & Founding

Where Idaho Was Born

On August 2, 1862, prospectors discovered gold near present-day Centerville in what would become Boise County. Within months, the Boise Basin gold rush — the largest since the California rush of 1849 — drew tens of thousands of miners into the mountains. By end of 1862, the basin's four major camps (Idaho City, Placerville, Centerville, Pioneerville) had grown into the four largest settlements in all of Washington Territory.

The sheer scale of the rush forced political action: the population influx was so massive that Idaho Territory was created in 1863 largely to govern the Boise Basin. The basin ultimately produced more gold than the entire state of Alaska — an almost incomprehensible figure that established Idaho City, at its peak in the mid-1860s, as the largest city in the entire Pacific Northwest.

Boise County was formally established on February 4, 1864 by the Idaho Territorial Legislature, named for the Boise River. The county is one of only four Idaho counties that also existed under Washington Territory, making it among the oldest governmental units in the state. The historic Boise County Courthouse at 419 Main Street, Idaho City, is considered one of Idaho's most historically significant buildings.

1862
Gold Discovered
August 2 — gold found near Centerville. Within weeks the Boise Basin gold rush begins — the largest in American history since California 1849.
1862
Idaho City Founded
Founded in December as "Bannock City" near the confluence of Elk and Mores Creeks. Population explodes to 6,000+ within a year; 250 places of business.
1863
Idaho Territory Created
The Boise Basin population boom directly prompts Congress to establish Idaho Territory. Idaho City briefly serves as the largest city in the Pacific Northwest.
1864
Boise County Established
February 4 — the Idaho Territorial Legislature formally creates Boise County with Idaho City as county seat. Named for the Boise River.
1908
Boise National Forest
Boise National Forest established under President Theodore Roosevelt's conservation orders, protecting the county's vast timberlands from unregulated logging.
1972
Sawtooth Wilderness Designated
Public Law 92-400 designates the Sawtooth Wilderness (217,088 acres), the western portion of which lies along Boise County's eastern border. Signed by President Nixon.
Communities

Places Within Boise County

Connected by the Ponderosa Pine Scenic Byway (Hwy 21) and Payette River Scenic Byway (Hwy 55). The closest thing to a traffic signal in Boise County is a flashing red light at Highways 52 and 55 in Horseshoe Bend.

County Seat
Idaho City
Established December 1862 as Bannock City. At its 1860s peak, the largest city in the Pacific Northwest. Today a preserved historic townsite 40 miles northeast of Boise. The Boise County Courthouse (419 Main St), the 1867 post office building, and the former Miners Exchange Saloon anchor the historic district. Elevation 3,944 ft.

idahocity.org →
Explore Idaho City
Largest City
Horseshoe Bend
On the Payette River along State Highway 55, at approximately 2,744 ft elevation. Originally a gold miners' staging area where prospectors waited for mountain snows to thaw. Renamed from Warrinersville in 1867. Now an affordable small-town community within commute distance of Boise, on the Payette River Scenic Byway.
River Community
Garden Valley & Crouch
A lush valley along the South Fork of the Payette River. Crouch (established 1934) serves as the commercial center. First settled by fur trappers, then gold rush era farmers supplying the basin camps. Known for hot springs, fishing, and mountain access.

gardenvalleyidaho.org →
Garden Valley
Geothermal Zone
Lowman
Remote community on Hwy 21 in eastern Boise County, approximately 68 miles northeast of Boise. Settled in a geothermal active region — natural hot springs surface in the middle of the community and throughout the surrounding mountains. Gateway to the Sawtooth region and Stanley beyond. Population ~42 (2010 census).
Whitewater Hub
Banks
Located at the confluence of the North and South Forks of the Payette River on Hwy 55. Population 17 (2010). Despite its size, Banks is the launch point for some of the West's finest whitewater — the "Main" Payette run begins here, and the Class IV "Staircase" section of the South Fork ends here.
Gold Rush Ghost Town
Placerville
Founded December 1, 1862. By early summer 1863 the town had 300 buildings and a population of 5,000. Named for placer mining in the vicinity, it was unusual among gold camps for having a true street grid and town square. Located 17 miles east of Horseshoe Bend at ~4,300 ft elevation. Semi-ghost town, still inhabited. Roof snow load: 150 lbs/sq ft — among the highest in the county.
Additional Communities
Centerville (site of the first 1862 gold discovery), Pioneerville (early gold camp, "Hogem"), Grimes Pass, Quartzburg, Gardena, Twin Springs, Robie Creek, Star Ranch, Banner, Granite — all connected by a network of paved and unpaved roads through the Boise Basin.
Recreation & Land

Mountain Recreation in Every Direction

Boise County sits at the confluence of world-class skiing, whitewater, wilderness, and scenic byways — most of it within 90 minutes of downtown Boise.

Skiing & Nordic
Bogus Basin Mountain Recreation Area
Located 16 miles north-northeast of Boise entirely within Boise County. Non-profit ski resort on the Boise National Forest. 2,600 skiable acres, 90 trails (22% beginner / 45% intermediate / 33% expert), 1,790 ft vertical drop, top elevation 7,582 ft, average 250 inches annual snowfall. Night skiing 7 nights/week. 23 miles of Nordic trails. Website: bogusbasin.org
Bogus Basin →
Whitewater — Class I–V
Payette River System
The Payette River and its forks flow through Boise County offering the full spectrum of whitewater. The Main Payette (Banks to Beehive Bend): Class II–III. The South Fork Staircase: Class II–III. The South Fork Canyon (Deadwood to Danskin): Class III–V. Jointly managed by the BLM and Boise National Forest. Best flows May–August; snowmelt extends the season. Payette River Corridor on Recreation.gov
BLM River Guide →
Wilderness
Sawtooth Wilderness
The central section of the Sawtooth Wilderness (217,088 acres total) lies along Boise County's eastern border. Thompson Peak at 10,751 ft (3,277 m) is the county's highest point. Designated by Public Law 92-400 on August 22, 1972. Part of the Sawtooth National Recreation Area (730,864 acres). Managed by Sawtooth National Forest. Access via Hwy 21 through Lowman.
Sawtooth NF →
Scenic Byways
Two National Scenic Routes
Boise County's two primary roads are both designated scenic byways. Hwy 21 — Ponderosa Pine Scenic Byway: Boise → Idaho City → Lowman → Stanley (Custer County). Hwy 55 — Payette River Scenic Byway: Eagle → Horseshoe Bend → Banks → McCall — a nationally designated scenic byway. Both routes are two-lane undivided highways through mountain terrain; winter driving conditions apply.
Geothermal
Hot Springs — Lowman Region
Lowman and its surrounding mountains sit in a geothermal active zone. Natural hot springs surface throughout the community and in the mountains along the upper Payette corridor. The area's geothermal character also shaped the ecology of the upper Boise Basin and continues to attract visitors year-round, particularly after winter skiing at Bogus Basin and backcountry trips into the Sawtooth.
Forest
Boise National Forest
The Boise National Forest blankets the majority of Boise County — 2.9 million acres total across the forest, established 1908 under President Roosevelt. Camping, fly fishing, hiking, mountain biking, OHV trails, and remote cabin rentals. The Boise River system originates in the forest's eastern reaches. Day-use parking: Recreation.gov or Boise NF Annual Pass ($30).
Boise National Forest →
Geography & Land

The Lay of the Land

Boise County spans 1,907 square miles (4,940 km²) of central Idaho mountain terrain. Of this, 1,899 square miles is land and 7.4 square miles is water. The county is bounded by the rugged terrain of the Sawtooth Range to the east, drops into the Payette River canyon on its western side, and encompasses the entire Boise Basin at its core.

Elevation varies dramatically. Horseshoe Bend on the Payette River sits at approximately 2,700 ft. Idaho City (the county seat) at 3,944 ft. The gold rush era communities of Placerville, Centerville, and Star Ranch average 4,300 ft. The county climbs all the way to Thompson Peak at 10,751 ft on the eastern Sawtooth boundary. This range means Placerville roofs are engineered to hold 150 lbs/sq ft of snow — nearly three times the load required at Horseshoe Bend.

The Payette River system drains the majority of the county. The North Fork, South Fork, and Middle Fork converge near Banks on the western edge, feeding the whitewater corridor that draws thousands of visitors annually. The upper Boise River originates in the county's eastern reaches within the Boise National Forest.

In 2010, the geographic center of Idaho's entire population was located within Boise County — a reflection of the county's central position within the state and its proximity to the booming Treasure Valley to the south.

Thompson Peak — 10,751 ft
Highest point in Boise County, on the eastern border within the Sawtooth Wilderness.
Ponderosa Pine Scenic Byway — Hwy 21
Boise → Idaho City → Lowman → Stanley. The primary artery through Boise County. Scenic Byways info →
Payette River Scenic Byway — Hwy 55
Eagle → Horseshoe Bend → Banks → McCall. Nationally designated scenic byway. Visit Idaho info →
North Fork + South Fork → Banks
Confluence of the Payette River forks at Banks. Class I–V whitewater access. BLM/Forest Service fee site. BLM corridor info →
Sawtooth NRA — Western Portion
The western portion of the Sawtooth National Recreation Area (730,864 acres total, est. 1972) extends into Boise County's eastern reaches.
Boise Metropolitan Area
Boise County is part of the Boise MSA, which is approaching 900,000 residents across Ada, Canyon, Gem, Owyhee, and Boise counties.
County Government

Governance & Services

Boise County is governed by a Board of County Commissioners headquartered at 420 Main Street, Idaho City. County offices include the Clerk/Auditor/Recorder, Assessor, Treasurer, Sheriff, Prosecutor, Planning & Zoning, Road & Bridge, and Waste Management. The official county website is boisecounty.us.

The County Clerk serves as ex-officio Auditor and Recorder. The clerk records deeds, mortgages, powers of attorney, water rights, and other real property instruments — an essential function in a county where land transactions are tied to significant recreational and residential value. The courthouse also issues passport services by appointment.

Boise County is within Idaho's 1st Congressional District. For state legislature representation, the county falls within an Idaho Senate and House district covering the Boise Basin area.

Regional Network

Boise County in Context

Boise County is surrounded by and contains some of Idaho's most significant natural and historical places. These are the essential regional entities.

County Seat
Idaho City
The historic county seat. Gold rush origin, Pacific Northwest's largest city in the 1860s. 40 miles northeast of Boise on Hwy 21.
idahocity.org
National Forest
Boise National Forest
2.9 million acres. Covers most of Boise County. Bogus Basin, Payette River corridor, remote cabins, fly fishing. Est. 1908.
boisenationalforest.org
Community
Garden Valley
South Fork Payette River valley. Hot springs, fishing, mountain community within Boise County, 60 miles from Boise.
gardenvalleyidaho.org
Wilderness
Frank Church Wilderness
River of No Return — largest contiguous wilderness in the lower 48 states. Adjacent wilderness corridor to the north of Boise County.
frankchurchwilderness.org
National Forest
Sawtooth National Forest
Manages the Sawtooth Wilderness and SNRA on Boise County's eastern border. Stanley, Redfish Lake, the White Cloud Peaks.
sawtoothnationalforest.org
Authority
Boise Standard
Regional knowledge network and verification authority for Boise County and the greater Treasure Valley region. Publisher of this record.
boisestandard.org
Federal / BLM
Payette River (BLM)
BLM-managed whitewater corridor. Class I–V rapids, fee site, jointly managed with Boise National Forest. Recreation.gov access.
BLM Payette River
Recreation
Bogus Basin
Non-profit ski resort entirely within Boise County. 2,600 acres, 16 miles from Boise. Nordic trails, night skiing, 250" avg snowfall.
bogusbasin.org
Start with Idaho City

The county seat — gold rush history, Ponderosa pines, and 40 miles of mountain road from Boise. The best single destination in Boise County.

◈ Idaho City — idahocity.org Boise Standard →