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List of counties in Idaho facts for kids

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Counties of Idaho
Location State of Idaho
Number 44
Populations 982 (Clark) – 392,365 (Ada)
Areas 408 square miles (1,060 km2) (Payette) – 8,485 square miles (21,980 km2) (Idaho)
Government County government
Subdivisions cities, towns, townships, unincorporated communities, indian reservations, census designated place

This is a list of 44 counties in the U.S. state of Idaho.

Each county in Idaho has a license plate prefix, according to the first letter of the county name. The first county for a given letter is given #1, the second county #2, etc. For example, Ada and Adams are the only two counties with the letter 'A'. Since Ada comes before Adams alphabetically, Ada is '1A' while Adams is '2A.' There are four counties that start with the letter 'L': Latah, Lemhi, Lewis, and Lincoln; the license plate prefixes for these counties are 1L, 2L, 3L, and 4L, respectively.

Elmore, Idaho, Kootenai, Nez Perce, Shoshone, Valley, and Washington counties are the only ones in the state with those beginning letters. Therefore, the license plate prefix would be the first letter of the county name, without a number. The letter 'B' has ten counties, 'C' has seven, and 'L' has four; the remaining letters have two or fewer.

When the Idaho Territory was created in March 1863, there were five original counties: Shoshone, Nez Perce, Idaho, Boise, and Missoula. Kootenai, Owyhee, and Oneida were created by 1865, Ada was created in 1866, and when the territory reached Idaho's present day dimensions in 1868, Lemhi was formed. By 1880, 13 counties were created. Ten years later, when Idaho became a state, 18 counties were created. In 1893, Fremont and Bannock counties were created. By 1900, Idaho had 21 counties. Ten years later, only two new counties were created. Between 1910 and 1920, 21 new counties were created, bringing the number of counties to 44, where it remains today.

Alphabetical list

FIPS code County seat Established Origin License Plate Designator Etymology
Population Area Map
Ada County 001 Boise 1864 Boise County 1A Ada Riggs, daughter of H. C. Riggs, a member of the Idaho Territorial Legislature. &&&&&&&&&0392365.&&&&&0392,365 &&&&&&&&&&&01055.&&&&&01,055 sq mi
(&&&&&&&&&&&02732.&&&&&02,732 km2)
State map highlighting Ada County
Adams County 003 Council 1911 Washington County 2A John Adams (1735-1826), second President of the United States (1797-1801). &&&&&&&&&&&03976.&&&&&03,976 &&&&&&&&&&&01365.&&&&&01,365 sq mi
(&&&&&&&&&&&03535.&&&&&03,535 km2)
State map highlighting Adams County
Bannock County 005 Pocatello 1893 Bingham County 1B Bannock Native American tribe. &&&&&&&&&&082839.&&&&&082,839 &&&&&&&&&&&01113.&&&&&01,113 sq mi
(&&&&&&&&&&&02883.&&&&&02,883 km2)
State map highlighting Bannock County
Bear Lake County 007 Paris 1893 Oneida County 2B Bear Lake on the Utah/Idaho border. &&&&&&&&&&&05986.&&&&&05,986 &&&&&&&&&&&&0971.&&&&&0971 sq mi
(&&&&&&&&&&&02515.&&&&&02,515 km2)
State map highlighting Bear Lake County
Benewah County 009 St. Maries 1915 Kootenai County 3B Ben'wah, chief of the Coeur d'Alene Tribe &&&&&&&&&&&09285.&&&&&09,285 &&&&&&&&&&&&0776.&&&&&0776 sq mi
(&&&&&&&&&&&02010.&&&&&02,010 km2)
State map highlighting Benewah County
Bingham County 011 Blackfoot 1885 Oneida County 4B Henry H. Bingham (1841-1912), a general in the American Civil War and a U.S. Congressman from Pennsylvania. &&&&&&&&&&045607.&&&&&045,607 &&&&&&&&&&&02095.&&&&&02,095 sq mi
(&&&&&&&&&&&05426.&&&&&05,426 km2)
State map highlighting Bingham County
Blaine County 013 Hailey 1895 Alturas County 5B James G. Blaine (1830-1893), United States Secretary of State (1881, 1889-1892). &&&&&&&&&&021376.&&&&&021,376 &&&&&&&&&&&02645.&&&&&02,645 sq mi
(&&&&&&&&&&&06851.&&&&&06,851 km2)
State map highlighting Blaine County
Boise County 015 Idaho City 1864 Original county 6B Boise River &&&&&&&&&&&07028.&&&&&07,028 &&&&&&&&&&&01902.&&&&&01,902 sq mi
(&&&&&&&&&&&04926.&&&&&04,926 km2)
State map highlighting Boise County
Bonner County 017 Sandpoint 1907 Kootenai County 7B Edwin L. Bonner, originator of an 1864 ferry service on the Kootenai River. &&&&&&&&&&040877.&&&&&040,877 &&&&&&&&&&&01738.&&&&&01,738 sq mi
(&&&&&&&&&&&04501.&&&&&04,501 km2)
State map highlighting Bonner County
Bonneville County 019 Idaho Falls 1911 Bingham County 8B Benjamin Bonneville (1796-1878), a French-born explorer of the West. &&&&&&&&&0104234.&&&&&0104,234 &&&&&&&&&&&01869.&&&&&01,869 sq mi
(&&&&&&&&&&&04841.&&&&&04,841 km2)
State map highlighting Bonneville County
Boundary County 021 Bonners Ferry 1915 Bonner 9B Borders Canada on the north. &&&&&&&&&&010972.&&&&&010,972 &&&&&&&&&&&01269.&&&&&01,269 sq mi
(&&&&&&&&&&&03287.&&&&&03,287 km2)
State map highlighting Boundary County
Butte County 023 Arco 1917 Bingham, Blaine, and Jefferson counties 10B Buttes rising from the Snake River Plain. &&&&&&&&&&&02891.&&&&&02,891 &&&&&&&&&&&02233.&&&&&02,233 sq mi
(&&&&&&&&&&&05783.&&&&&05,783 km2)
State map highlighting Butte County
Camas County 025 Fairfield 1917 Blaine County 1C Camassia, a plant species important as a food source among Native Americans and early settlers. &&&&&&&&&&&01117.&&&&&01,117 &&&&&&&&&&&01075.&&&&&01,075 sq mi
(&&&&&&&&&&&02784.&&&&&02,784 km2)
State map highlighting Camas County
Canyon County 027 Caldwell 1892 Ada County 2C 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. &&&&&&&&&0188923.&&&&&0188,923 &&&&&&&&&&&&0590.&&&&&0590 sq mi
(&&&&&&&&&&&01528.&&&&&01,528 km2)
State map highlighting Canyon County
Caribou County 029 Soda Springs 1919 Bannock County 3C Caribou Mountains &&&&&&&&&&&06963.&&&&&06,963 &&&&&&&&&&&01766.&&&&&01,766 sq mi
(&&&&&&&&&&&04574.&&&&&04,574 km2)
State map highlighting Caribou County
Cassia County 031 Burley 1879 Owyhee County 4C Disputed, either Cassia Creek or a member of the Mormon Battalion, James John Cazier. &&&&&&&&&&022952.&&&&&022,952 &&&&&&&&&&&02567.&&&&&02,567 sq mi
(&&&&&&&&&&&06648.&&&&&06,648 km2)
State map highlighting Cassia County
Clark County 033 Dubois 1919 Fremont County 5C Sam K. Clark, early settler and a member of the Idaho Senate. &&&&&&&&&&&&0982.&&&&&0982 &&&&&&&&&&&01765.&&&&&01,765 sq mi
(&&&&&&&&&&&04571.&&&&&04,571 km2)
State map highlighting Clark County
Clearwater County 035 Orofino 1911 Nez Perce County 6C Clearwater River &&&&&&&&&&&08761.&&&&&08,761 &&&&&&&&&&&02462.&&&&&02,462 sq mi
(&&&&&&&&&&&06377.&&&&&06,377 km2)
State map highlighting Clearwater County
Custer County 037 Challis 1881 Alturas and Lemhi counties 7C General Custer mine, named after George Armstrong Custer (1839-1876), United States Army general. &&&&&&&&&&&04368.&&&&&04,368 &&&&&&&&&&&04926.&&&&&04,926 sq mi
(&&&&&&&&&&012758.&&&&&012,758 km2)
State map highlighting Custer County
Elmore County 039 Mountain Home 1889 Alturas County E Ida Elmore mines, locally noted for gold and silver production in the 1860s. &&&&&&&&&&027038.&&&&&027,038 &&&&&&&&&&&03078.&&&&&03,078 sq mi
(&&&&&&&&&&&07972.&&&&&07,972 km2)
State map highlighting Elmore County
Franklin County 041 Preston 1913 Oneida County 1F Franklin D. Richards (1821-1899), early LDS Church apostle. &&&&&&&&&&012786.&&&&&012,786 &&&&&&&&&&&&0666.&&&&&0666 sq mi
(&&&&&&&&&&&01725.&&&&&01,725 km2)
State map highlighting Franklin County
Fremont County 043 Saint Anthony 1893 Bingham County 2F John C. Frémont (1813-1890), an explorer of the West. &&&&&&&&&&013242.&&&&&013,242 &&&&&&&&&&&01867.&&&&&01,867 sq mi
(&&&&&&&&&&&04836.&&&&&04,836 km2)
State map highlighting Fremont County
Gem County 045 Emmett 1915 Boise and Canyon counties 1G State nickname of "Gem State." &&&&&&&&&&016719.&&&&&016,719 &&&&&&&&&&&&0563.&&&&&0563 sq mi
(&&&&&&&&&&&01458.&&&&&01,458 km2)
State map highlighting Gem County
Gooding County 047 Gooding 1913 Lincoln County 2G Frank R. Gooding (1859-1928), seventh Governor of Idaho (1905-1909), U.S. Senator (1921-1928). &&&&&&&&&&015464.&&&&&015,464 &&&&&&&&&&&&0731.&&&&&0731 sq mi
(&&&&&&&&&&&01893.&&&&&01,893 km2)
State map highlighting Gooding County
Idaho County 049 Grangeville 1864 Original county I Columbia River steamship Idaho launched in 1860. Name predates both Idaho Territory and the State of Idaho. &&&&&&&&&&016267.&&&&&016,267 &&&&&&&&&&&08485.&&&&&08,485 sq mi
(&&&&&&&&&&021976.&&&&&021,976 km2)
State map highlighting Idaho County
Jefferson County 051 Rigby 1913 Fremont County 1J Thomas Jefferson (1743-1826), third President of the United States (1801-1809). &&&&&&&&&&026140.&&&&&026,140 &&&&&&&&&&&01095.&&&&&01,095 sq mi
(&&&&&&&&&&&02836.&&&&&02,836 km2)
State map highlighting Jefferson County
Jerome County 053 Jerome 1919 Gooding and Lincoln counties 2J Disputed, either North Side Irrigation Project developer Jerome Hill, his son-in-law Jerome Kuhn, or his grandson Jerome Kuhn, Jr. &&&&&&&&&&022374.&&&&&022,374 &&&&&&&&&&&&0600.&&&&&0600 sq mi
(&&&&&&&&&&&01554.&&&&&01,554 km2)
State map highlighting Jerome County
Kootenai County 055 Coeur d'Alene 1864 Nez Perce County K Kootenai Native American tribe. &&&&&&&&&0138494.&&&&&0138,494 &&&&&&&&&&&01245.&&&&&01,245 sq mi
(&&&&&&&&&&&03225.&&&&&03,225 km2)
State map highlighting Kootenai County
Latah County 057 Moscow 1888 Nez Perce County 1L Latah Creek, Nez Perce for "the place of pine trees and sestle." &&&&&&&&&&037244.&&&&&037,244 &&&&&&&&&&&01077.&&&&&01,077 sq mi
(&&&&&&&&&&&02789.&&&&&02,789 km2)
State map highlighting Latah County
Lemhi County 059 Salmon 1869 Idaho County 2L Limhi, king of the Nephites according to the Book of Mormon. &&&&&&&&&&&07936.&&&&&07,936 &&&&&&&&&&&04564.&&&&&04,564 sq mi
(&&&&&&&&&&011821.&&&&&011,821 km2)
State map highlighting Lemhi County
Lewis County 061 Nezperce 1911 Nez Perce County 3L Meriwether Lewis (1774-1809), a leader of the Lewis and Clark Expedition. &&&&&&&&&&&03821.&&&&&03,821 &&&&&&&&&&&&0479.&&&&&0479 sq mi
(&&&&&&&&&&&01241.&&&&&01,241 km2)
State map highlighting Lewis County
Lincoln County 063 Shoshone 1895 Logan County 4L Abraham Lincoln (1809-1865), sixteenth President of the United States (1861-1865). Idaho Territory was founded under Lincoln's administration. &&&&&&&&&&&05208.&&&&&05,208 &&&&&&&&&&&01206.&&&&&01,206 sq mi
(&&&&&&&&&&&03124.&&&&&03,124 km2)
State map highlighting Lincoln County
Madison County 065 Rexburg 1913 Fremont County 1M James Madison (1751-1836), fourth President of the United States (1809-1817). &&&&&&&&&&037536.&&&&&037,536 &&&&&&&&&&&&0472.&&&&&0472 sq mi
(&&&&&&&&&&&01222.&&&&&01,222 km2)
State map highlighting Madison County
Minidoka County 067 Rupert 1913 Lincoln County 2M Disputed Native American origin, either Lakota for "a fountain or spring of water" or Shoshoni for "broad expanse." &&&&&&&&&&020069.&&&&&020,069 &&&&&&&&&&&&0760.&&&&&0760 sq mi
(&&&&&&&&&&&01968.&&&&&01,968 km2)
State map highlighting Minidoka County
Nez Perce County 069 Lewiston 1864 Original county N The Nez Perce, a Native American tribe. &&&&&&&&&&039265.&&&&&039,265 &&&&&&&&&&&&0849.&&&&&0849 sq mi
(&&&&&&&&&&&02199.&&&&&02,199 km2)
State map highlighting Nez Perce County
Oneida County 071 Malad City 1864 Original County 1O Oneida Lake in New York state, where many early settlers were from. &&&&&&&&&&&04286.&&&&&04,286 &&&&&&&&&&&01200.&&&&&01,200 sq mi
(&&&&&&&&&&&03108.&&&&&03,108 km2)
State map highlighting Oneida County
Owyhee County 073 Murphy 1863 Original county 2O Alternate spelling of Hawaii. Hawaiian fur trappers explored the area in 1819 and 1820. &&&&&&&&&&011526.&&&&&011,526 &&&&&&&&&&&07678.&&&&&07,678 sq mi
(&&&&&&&&&&019886.&&&&&019,886 km2)
State map highlighting Owyhee County
Payette County 075 Payette 1917 Canyon County 1P Francois Payette (1793-1844?), Canadian-born fur trader and early settler. &&&&&&&&&&022623.&&&&&022,623 &&&&&&&&&&&&0408.&&&&&0408 sq mi
(&&&&&&&&&&&01057.&&&&&01,057 km2)
State map highlighting Payette County
Power County 077 American Falls 1913 Bingham, Blaine, and Oneida counties 2P The American Falls Power Plant &&&&&&&&&&&07817.&&&&&07,817 &&&&&&&&&&&01406.&&&&&01,406 sq mi
(&&&&&&&&&&&03642.&&&&&03,642 km2)
State map highlighting Power County
Shoshone County 079 Wallace 1864 Original county S Shoshone Native American tribe. &&&&&&&&&&012765.&&&&&012,765 &&&&&&&&&&&02634.&&&&&02,634 sq mi
(&&&&&&&&&&&06822.&&&&&06,822 km2)
State map highlighting Shoshone County
Teton County 081 Driggs 1915 Bingham, Fremont, and Madison counties 1T Teton Range in Wyoming. &&&&&&&&&&010170.&&&&&010,170 &&&&&&&&&&&&0450.&&&&&0450 sq mi
(&&&&&&&&&&&01165.&&&&&01,165 km2)
State map highlighting Teton County
Twin Falls County 083 Twin Falls 1907 Cassia County 2T Twin Falls waterfall on the Snake River. &&&&&&&&&&077230.&&&&&077,230 &&&&&&&&&&&01925.&&&&&01,925 sq mi
(&&&&&&&&&&&04986.&&&&&04,986 km2)
State map highlighting Twin Falls County
Valley County 085 Cascade 1917 Boise and Idaho counties V Long Valley located in the county. &&&&&&&&&&&09862.&&&&&09,862 &&&&&&&&&&&03733.&&&&&03,733 sq mi
(&&&&&&&&&&&09668.&&&&&09,668 km2)
State map highlighting Valley County
Washington County 087 Weiser 1879 Ada County W George Washington (1732-1799), first President of the United States (1789-1797). &&&&&&&&&&010198.&&&&&010,198 &&&&&&&&&&&01456.&&&&&01,456 sq mi
(&&&&&&&&&&&03771.&&&&&03,771 km2)
State map highlighting Washington County

Remember the counties

In some fourth grade classrooms, students memorize the counties with the following poem:

Counties of Idaho Poem
Ada is first with our capital town,
Adams’ Seven Devils go straight up and down.
Then ten counties start with B;
Bannock, Bear Lake, Benewah three;
Bingham, Blaine, Boise, Bonner,
Bonneville, Boundary, Butte make ten.
Then the next seven start with C:
Camas, Canyon, Caribou three.
Cassia, Clark, Clearwater, Custer,
Are the Idaho C’s we can muster.
Elmore, Franklin, Fremont, Gem,
Gooding and Idaho don’t forget them.
Flatlands of Jefferson,
Potatoes of Jerome,
Kootenai, Latah, we’re almost home.
Lemhi and Lewis,
Hurry, hurry, hurry!
Lincoln with its ice caves
Very very burry.
Madison, Minidoka, Nez Perce;
Our Indian accent grows worse and worse.
Oneida, Owyhee, a little faster please
Payette and Power are the only Ps.
Shoshone, Teton, Twin Falls, almost done,
Valley County and Washington.
Author unknown

Defunct Idaho counties

  • Alturas County: A huge county in south-central Idaho that was formed in 1864, but split up and abolished in 1895.
  • Lah-Toh County: A county in northern Idaho that was formed in 1864, but it was abolished a short time later in 1867.
  • Logan County: Formed by a partition of Alturas County in 1889, but it was shortly abolished in 1895.
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