History and Facts of Idaho Counties
List of Idaho Counties
Idaho is divided into 44 counties.
|County||Created||Created From||Named For||County Seat||Notes|
|Ada County||22 Dec 1864||Boise County||Ada Riggs, daughter of H. C. Riggs, a member of the Idaho Territorial Legislature.||Boise|
|Adams County||03 Mar 1911||Washington County||John Adams (1735-1826), second President of the United States (1797-1801).||Council|
|Bannock County||06 Mar 1839||Bingham County||Bannock Native American tribe.||Pocatello|
|Benewah County||05 Jan 1875||Oneida County||Bear Lake on the Utah/Idaho border.||Paris|
|Bingham County||25 Jan 1915||Kootenai County||Ben'wah, chief of the Coeur d'Alene Tribe||St. Maries|
|Bear Lake County||13 Jan 1885||Oneida County||Henry H. Bingham (1841-1912), a general in the American Civil War and a U.S. Congressman from Pennsylvania.||Blackfoot|
|Blaine County||05 Mar 1895||Alturas||James G. Blaine (1830-1893), United States Secretary of State (1881, 1889-1892).||Hailey|
|Bonner County||12 Jan 1863||Original county||Boise River||Idaho City|
|Boise County||21 Feb 1907||Kootenai County||Edwin L. Bonner, originator of an 1864 ferry service on the Kootenai River.||Sandpoint|
|Boundary County||07 Feb 1911||Bingham County||Benjamin Bonneville (1796-1878), a French-born explorer of the West.||Idaho Falls|
|Butte County||23 Jan 1915||Bonner||Borders Canada on the north.||Bonners Ferry|
|Bonneville County||06 Feb 1917||Bingham, Blaine, and Jefferson counties||Buttes rising from the Snake River Plain.||Arco|
|Camas County||06 Feb 1917||Blaine County||Camassia, a plant species important as a food source among Native Americans and early settlers.||Fairfield|
|Canyon County||07 Mar 1891||Ada County||Disputed, either a canyon of the Boise River near Caldwell or a canyon of the Snake River which forms part of the county's boundary.||Caldwell|
|Caribou County||11 Feb 1919||Bannock County||Caribou Mountains||Soda Springs|
|Cassia County||20 Feb 1879||Owyhee County||Disputed, either Cassia Creek or a member of the Mormon Battalion, James John Cazier.||Burley|
|Clark County||01 Feb 1919||Fremont County||Sam K. Clark, early settler and a member of the Idaho Senate.||Dubois|
|Custer County||27 Feb 1911||Nez Perce County||Clearwater River||Orofino|
|Clearwater County||08 Jan 1881||Alturas and Lemhi counties||General Custer mine, named after George Armstrong Custer (1839-1876), United States Army general.||Challis|
|Elmore County||07 Feb 1889||Alturas||Ida Elmore mines, locally noted for gold and silver production in the 1860s.||Mountain Home|
|Franklin County||30 Jan 1913||Oneida County||Franklin D. Richards (1821-1899), early LDS Church apostle.||Preston|
|Fremont County||04 Mar 1893||Bingham County||John C. Frémont (1813-1890), an explorer of the West.||Saint Anthony|
|Gem County||19 Mar 1915||Boise and Canyon counties||State nickname of "Gem State."||Emmett|
|Gooding County||28 Jan 1913||Lincoln County||Frank R. Gooding (1859-1928), seventh Governor of Idaho (1905-1909), U.S. Senator(1921-1928).||Gooding|
|Idaho County||04 Feb 1864||Original county||Columbia River steamship Idaho launched in 1860. Name predates both Idaho Territory and the State of Idaho.||Grangeville|
|Jefferson County||18 Feb 1913||Fremont County||Thomas Jefferson (1743-1826), third President of the United States (1801-1809).||Rigby|
|Jerome County||08 Feb 1919||Gooding and Lincoln counties||Disputed, either North Side Irrigation Project developer Jerome Hill, his son-in-law Jerome Kuhn, or his grandson Jerome Kuhn, Jr.||Jerome|
|Kootenai County||22 Dec 1864||Nez Perce County||Kootenai Native American tribe.||Coeur d'Alene|
|Latah County||22 Dec 1864||Nez Perce County||Latah Creek, Nez Perce for "the place of pine trees and sestle."||Moscow|
|Lincoln County||09 Jan 1869||Idaho County||Limhi, king of the Nephites according to the Book of Mormon.||Salmon|
|Lemhi County||03 Mar 1911||Nez Perce County||Meriwether Lewis (1774-1809), a leader of the Lewis and Clark Expedition.||Nezperce|
|Lewis County||18 Mar 1895||Logan||Abraham Lincoln (1809-1865), sixteenth President of the United States (1861-1865). Idaho Territory was founded under Lincoln's administration.||Shoshone|
|Madison County||18 Feb 1913||Fremont County||James Madison (1751-1836), fourth President of the United States (1809-1817).||Rexburg|
|Minidoka County||28 Jan 1913||Lincoln County||Disputed Native American origin, either Lakota for "a fountain or spring of water" or Shoshoni for "broad expanse."||Rupert|
|Nez Perce County||20 Dec 1861||Original county||The Nez Perce, a Native American tribe.||Lewiston|
|Oneida County||22 Jan 1864||Original County||Oneida Lake in New York state, where many early settlers were from.||Malad City|
|Owyhee County||31 Dec 1863||Original county||Alternate spelling of Hawaii. Hawaiian fur trappers explored the area in 1819 and 1820.||Murphy|
|Payette County||28 Feb 1917||Canyon County||Francois Payette (1793-1844?), Canadian-born fur trader and early settler.||Payette|
|Power County||30 Jan 1913||Bingham, Blaine, and Oneida counties||The American Falls Power Plant||American Falls|
|Shoshone County||04 Feb 1864||Original county||Shoshone Native American tribe.||Wallace|
|Teton County||26 Jan 1915||Bingham, Fremont, and Madison counties||Teton Range in Wyoming.||Driggs|
|Twin Falls County||21 Feb 1907||Cassia County||Twin Falls waterfall on the Snake River.||Twin Falls|
|Valley County||26 Feb 1917||Boise and Idaho counties||Long Valley located in the county.||Cascade|
|Washington County||20 Feb 1879||Ada County||George Washington (1732-1799), first President of the United States (1789-1797).||Weiser|
|Old Alta County (Extinct)||03 Mar 1891||Alturas County|
|Old Alturas County (Extinct)||04 Feb 1864||Boise County|
|Old Lah-Toh County (Extinct)||22 Dec 1864||Idaho Territory|
|Old Logan County (Extinct)||07 Feb 1889||Alturas County|
|Old Yellowstone County (Extinct)||07 Feb 1889||Idaho Territory from Non-County Area||was located entirely within present Wyoming|
List of Old Former / Extinct Idaho Counties
Idaho has counties that no longer are in existence. A lot of these counties were established and disbanded within the 19th century; county borders have modified very little since 1900 in the vast most of states.
The below Idaho counties no longer exist:
?? County, Idaho
- Alturas County(1864-1895) – was a county in Idaho Territory and later the state of Idaho from 1864 to 1895. It covered an area larger than the states of Maryland, New Jersey, and Delaware combined. Most present-day southern Idaho counties were created at least in part from the original Alturas County area. The name Alturas comes from a Spanish word for “mountain summits” or “mountainous heights.” Alturas County was created by the Idaho Territorial Legislature in February 1864. Later that year the mining camp of Rocky Bar was designated the county seat. The county seat was moved to Hailey in 1882. In 1889, the Idaho Territorial Legislature created Elmore County and Logan County from parts of Alturas County. On March 5, 1895, to circumvent a recent state supreme court decision striking down an earlier county reorganization, the Idaho Legislature combined Alturas and Logan Counties into a new county called Blaine. Two weeks later on March 18, the southern portion of the newly-created Blaine County was split off to form Lincoln County with its county seat at Shoshone. Hailey remained the county seat of what was now Blaine County and Alturas County disappeared from the Idaho map.
- Lah-Toh County (1864-1867) – was a county in Idaho Territory from 1864 to 1867. Lah-Toh County was created by the Idaho Territorial Legislature in 1864 with Coeur d’Alene as its county seat. The name is Nez Perce for “the place of pine trees and sestle”. The county was abolished in 1867, although sources disagree whether the area was absorbed by Nez Perce County or Kootenai County. It is most likely Kootenai since Coeur d’Alene serves as that county’s county seat. The county was re-established in 1888 with different boundaries as Latah County.
- Logan County (1889-1895) – was a county in Idaho Territory and later the state of Idaho from 1889 to 1895. Logan County was created from parts of Alturas County by the Idaho Territorial Legislature in 1889 with Bellevue as its county seat. Six years later, the Idaho Legislature attempted to return Bellevue to Alturas County, but the plan was struck down by the state supreme court. In response on March 5, 1895, the Idaho Legislature combined Logan and Alturas Counties into a new county called Blaine. Two weeks later on March 18, the southern portion of the newly-created Blaine County was split off to form Lincoln County with its county seat at Shoshone and Logan County ceased to exist. Bellevue became part of Blaine County.
Map of Idaho County Boundary Changes from 1848 to 1965
This Interactive Map of Idaho Counties show the historical boundaries, names, organization, and attachments of every county, extinct county and unsuccessful county proposal from the creation of Idaho in 1848-1965.
Fun Facts about Idaho Counties
County Name Facts
The County names:
- 0 of them named for Native American words or people,
Counties by Year
Facts for County Size
- ? County (000 sq mi) is the largest county in Idaho.
- ? County (000 sq mi) is the smallest county in Idaho.
Facts for County Population (2017 Est.)
- ? County (000) is the most populated county in Idaho.
- ? County (000) is the least populated county in Idaho.
Facts for Idaho Counties and Cities
Idaho’s 10 largest cities (2010) are: