Idaho county map

How Idaho’s counties are laid out

Idaho’s 44 counties cover 83,569 square miles, so the average county is about 1,900 square miles, but the mountain counties in the centre are enormous and the farm counties of the Snake River Plain are small. The shape of the state explains the pattern: the Panhandle in the north is a strip 45 miles wide at the Canadian border, the central mountains are almost empty, and most people live along the Snake River across the south from Fremont County in the east to Canyon County in the west.

The oldest counties were organised by Washington Territory before Idaho Territory existed in 1863: Shoshone (1858, originally covering the whole Panhandle), Nez Perce, Idaho and Boise counties date from the 1861–1864 gold rushes. Most of the southern farm counties were created in a burst between 1907 and 1921 as irrigation from the Snake River opened new land; Jerome, Gooding, Minidoka, Power, Butte and Clark counties all date from those years.

Idaho is a split time-zone state. The ten northern counties — Benewah, Bonner, Boundary, Clearwater, Idaho (north of the Salmon River), Kootenai, Latah, Lewis, Nez Perce and Shoshone — keep Pacific Time with neighbouring Spokane, Washington; the rest of the state, including Boise, is on Mountain Time. The zone boundary runs along the Salmon River through Idaho County, so the county seat Grangeville is Pacific while Riggins, 40 miles south, is Mountain.

All 44 counties of Idaho

Five county facts

• Largest by area: Idaho County, about 8,500 square miles, the size of New Jersey, most of it national forest and the Frank Church–River of No Return Wilderness. Its seat, Grangeville, has fewer than 4,000 people. Owyhee County in the south-west desert is second, at about 7,700 square miles.
• Smallest by area: Payette County, seat Payette, about 410 square miles at the confluence of the Payette and Snake rivers on the Oregon line.
• Most populous: Ada County, seat Boise, with about 495,000 people in 2020 — more than one Idahoan in four. Canyon County next door (Caldwell and Nampa) is second with about 232,000; together the Treasure Valley counties hold two-fifths of the state.
• Least populous: Clark County, seat Dubois, on the Montana border north of Idaho Falls, with fewer than 800 people spread over 1,760 square miles. Camas County (Fairfield) is the next-smallest.
• Oldest and newest: Shoshone County, created in 1858 by Washington Territory, is the oldest; Nez Perce and Idaho counties followed in 1861. Jerome County, split from Gooding and Lincoln in 1919, is the newest. Idaho has no independent cities or consolidated city-counties.

Reading the map

Press Streets and zoom in on the highlighted state to see county lines. The Panhandle counties stack north to south — Boundary, Bonner, Kootenai, Benewah, Shoshone, Latah, Clearwater, Nez Perce, Lewis — and are separated from the south by the huge, road-less spread of Idaho, Lemhi, Custer and Valley counties. Lewiston in Nez Perce County, where the Clearwater joins the Snake, is the lowest point in the state (about 710 ft) and Idaho’s only seaport. The southern farm counties are arranged in two rows along the Snake River Plain: a western group around Boise and a chain of small, square counties from Twin Falls to Rexburg, with Pocatello (Bannock County) and Idaho Falls (Bonneville County) the main cities of the east. Bear Lake, Franklin and Oneida counties on the Utah line were settled from Utah and have the state’s oldest towns.

Related maps

• Idaho map — cities, borders and geography.
• Blank Idaho map and printable Idaho map.
• Boise, the state capital, in Ada County.
• Neighbouring county maps: Montana, Wyoming, Utah, Nevada, Oregon, Washington.
• Mountain division · the West · Pacific Northwest · Mountain and Pacific time zones.
• Geography: Snake River, Rocky Mountains, Continental Divide.
• All US county maps.