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List of counties in Idaho facts for kids

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Quick facts for kids
Counties of Idaho
Location State of Idaho
Number 44
Populations 801 (Clark) – 524,673 (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

Idaho is a state in the western United States. Like all U.S. states, Idaho is divided into smaller areas called counties. These counties help organize the state and provide local government services. Idaho has 44 counties, each with its own history and unique features.

How Idaho's Counties Were Formed

Idaho became a U.S. territory in March 1863. The very first county created was Owyhee County in December 1863. More counties quickly followed. Oneida County was formed in January 1864. Soon after, Shoshone, Nez Perce, Idaho, Boise, and Alturas Counties were recognized in February 1864. Kootenai and Ada Counties were created in December 1864.

Idaho's current borders were set in 1868. Lemhi County was created the next year. By 1890, when Idaho became the 43rd state, there were 18 counties. More counties were added over time. For example, Canyon, Fremont, and Bannock Counties were created. In 1895, two counties, Alturas and Logan, were combined to form Blaine County. Lincoln County was then formed from part of Blaine County.

Between 1911 and 1919, many new counties were created. This brought the total number of counties to 44, which is how many Idaho has today.

License Plate Codes

Since 1945, each Idaho county has a special code on its license plates. This code usually starts with the first letter of the county's name.

If several counties start with the same letter, a number is added before the letter. This number shows their order in an alphabetical list. For example, the four counties starting with 'L' are Latah, Lemhi, Lewis, and Lincoln. Their codes are 1L, 2L, 3L, and 4L.

Some counties are the only ones that start with their specific letter. These include Elmore, Idaho, Kootenai, Nez Perce, Shoshone, Valley, and Washington Counties. For these, only the letter is used as the code.

List of Idaho Counties

Here is a list of Idaho's 44 counties. It includes their county seat, when they were established, and what their name means.

County
FIPS code County seat Est. Origin License plate prefix Etymology
Population Area Map
Ada County 001 Boise 1864 Boise County 1A Named for Ada Riggs, daughter of a member of the Idaho Territorial Legislature. &&&&&&&&&0524673.&&&&&0524,673 &&&&&&&&&&&01055.&&&&&01,055 sq mi
(&&&&&&&&&&&02732.&&&&&02,732 km2)
State map highlighting Ada County
Adams County 003 Council 1911 Washington County 2A John Adams, the second President of the United States. &&&&&&&&&&&04903.&&&&&04,903 &&&&&&&&&&&01365.&&&&&01,365 sq mi
(&&&&&&&&&&&03535.&&&&&03,535 km2)
State map highlighting Adams County
Bannock County 005 Pocatello 1893 Bingham County 1B Named for the Bannock Native American tribe. &&&&&&&&&&090400.&&&&&090,400 &&&&&&&&&&&01113.&&&&&01,113 sq mi
(&&&&&&&&&&&02883.&&&&&02,883 km2)
State map highlighting Bannock County
Bear Lake County 007 Paris 1875 Oneida County 2B Named for Bear Lake on the Utah/Idaho border. &&&&&&&&&&&06766.&&&&&06,766 &&&&&&&&&&&&0971.&&&&&0971 sq mi
(&&&&&&&&&&&02515.&&&&&02,515 km2)
State map highlighting Bear Lake County
Benewah County 009 St. Maries 1915 Kootenai County 3B Named for Ben'wah, a chief of the Coeur d'Alene Tribe. &&&&&&&&&&010369.&&&&&010,369 &&&&&&&&&&&&0776.&&&&&0776 sq mi
(&&&&&&&&&&&02010.&&&&&02,010 km2)
State map highlighting Benewah County
Bingham County 011 Blackfoot 1885 Oneida County 4B Named for Henry H. Bingham, a general and U.S. Congressman. &&&&&&&&&&050395.&&&&&050,395 &&&&&&&&&&&02095.&&&&&02,095 sq mi
(&&&&&&&&&&&05426.&&&&&05,426 km2)
State map highlighting Bingham County
Blaine County 013 Hailey 1895 Alturas and Logan Counties 5B Named for James G. Blaine, a former United States Secretary of State. &&&&&&&&&&025041.&&&&&025,041 &&&&&&&&&&&02645.&&&&&02,645 sq mi
(&&&&&&&&&&&06851.&&&&&06,851 km2)
State map highlighting Blaine County
Boise County 015 Idaho City 1864 original county 6B Named for the Boise River. &&&&&&&&&&&08517.&&&&&08,517 &&&&&&&&&&&01902.&&&&&01,902 sq mi
(&&&&&&&&&&&04926.&&&&&04,926 km2)
State map highlighting Boise County
Bonner County 017 Sandpoint 1907 Kootenai County 7B Named for Edwin L. Bonner, who started a ferry service on the Kootenai River. &&&&&&&&&&052547.&&&&&052,547 &&&&&&&&&&&01738.&&&&&01,738 sq mi
(&&&&&&&&&&&04501.&&&&&04,501 km2)
State map highlighting Bonner County
Bonneville County 019 Idaho Falls 1911 Bingham County 8B Named for Benjamin Bonneville, a French-born explorer of the West. &&&&&&&&&0131366.&&&&&0131,366 &&&&&&&&&&&01869.&&&&&01,869 sq mi
(&&&&&&&&&&&04841.&&&&&04,841 km2)
State map highlighting Bonneville County
Boundary County 021 Bonners Ferry 1915 Bonner County 9B Named because it borders Canada to the north. &&&&&&&&&&013557.&&&&&013,557 &&&&&&&&&&&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 Named for the Buttes (isolated hills) rising from the Snake River Plain. &&&&&&&&&&&02758.&&&&&02,758 &&&&&&&&&&&02233.&&&&&02,233 sq mi
(&&&&&&&&&&&05783.&&&&&05,783 km2)
State map highlighting Butte County
Camas County 025 Fairfield 1917 Blaine County 1C Named for Camassia, a plant important for food to Native Americans and early settlers. &&&&&&&&&&&01232.&&&&&01,232 &&&&&&&&&&&01077.&&&&&01,077 sq mi
(&&&&&&&&&&&02789.&&&&&02,789 km2)
State map highlighting Camas County
Canyon County 027 Caldwell 1892 Ada County 2C Likely named for a canyon of the Boise River or the Snake River. &&&&&&&&&0257674.&&&&&0257,674 &&&&&&&&&&&&0590.&&&&&0590 sq mi
(&&&&&&&&&&&01528.&&&&&01,528 km2)
State map highlighting Canyon County
Caribou County 029 Soda Springs 1919 Bannock County 3C Named for the Caribou Mountains. &&&&&&&&&&&07219.&&&&&07,219 &&&&&&&&&&&01766.&&&&&01,766 sq mi
(&&&&&&&&&&&04574.&&&&&04,574 km2)
State map highlighting Caribou County
Cassia County 031 Burley 1879 Owyhee County 4C Named for Cassia Creek or James John Cazier, a member of the Mormon Battalion. &&&&&&&&&&025696.&&&&&025,696 &&&&&&&&&&&02567.&&&&&02,567 sq mi
(&&&&&&&&&&&06648.&&&&&06,648 km2)
State map highlighting Cassia County
Clark County 033 Dubois 1919 Fremont County 5C Named for Sam K. Clark, an early settler and Idaho Senator. &&&&&&&&&&&&0801.&&&&&0801 &&&&&&&&&&&01765.&&&&&01,765 sq mi
(&&&&&&&&&&&04571.&&&&&04,571 km2)
State map highlighting Clark County
Clearwater County 035 Orofino 1911 Nez Perce County 6C Named for the Clearwater River. &&&&&&&&&&&09214.&&&&&09,214 &&&&&&&&&&&02462.&&&&&02,462 sq mi
(&&&&&&&&&&&06377.&&&&&06,377 km2)
State map highlighting Clearwater County
Custer County 037 Challis 1881 Alturas and Lemhi Counties 7C Named for the General Custer mine, which was named after General George Armstrong Custer. &&&&&&&&&&&04523.&&&&&04,523 &&&&&&&&&&&04926.&&&&&04,926 sq mi
(&&&&&&&&&&012758.&&&&&012,758 km2)
State map highlighting Custer County
Elmore County 039 Mountain Home 1889 Alturas County E Named for the Ida Elmore mines, known for gold and silver. &&&&&&&&&&029724.&&&&&029,724 &&&&&&&&&&&03078.&&&&&03,078 sq mi
(&&&&&&&&&&&07972.&&&&&07,972 km2)
State map highlighting Elmore County
Franklin County 041 Preston 1913 Oneida County 1F Named for Franklin D. Richards, an early leader in the LDS Church. &&&&&&&&&&015494.&&&&&015,494 &&&&&&&&&&&&0666.&&&&&0666 sq mi
(&&&&&&&&&&&01725.&&&&&01,725 km2)
State map highlighting Franklin County
Fremont County 043 Saint Anthony 1893 Bingham County 2F Named for John C. Frémont, an explorer of the American West. &&&&&&&&&&014196.&&&&&014,196 &&&&&&&&&&&01867.&&&&&01,867 sq mi
(&&&&&&&&&&&04836.&&&&&04,836 km2)
State map highlighting Fremont County
Gem County 045 Emmett 1915 Boise and Canyon Counties 1G Named for Idaho's nickname, "Gem State." &&&&&&&&&&021071.&&&&&021,071 &&&&&&&&&&&&0563.&&&&&0563 sq mi
(&&&&&&&&&&&01458.&&&&&01,458 km2)
State map highlighting Gem County
Gooding County 047 Gooding 1913 Lincoln County 2G Named for Frank R. Gooding, a former Governor and U.S. Senator of Idaho. &&&&&&&&&&016061.&&&&&016,061 &&&&&&&&&&&&0731.&&&&&0731 sq mi
(&&&&&&&&&&&01893.&&&&&01,893 km2)
State map highlighting Gooding County
Idaho County 049 Grangeville 1864 original county I Named for the Columbia River steamship Idaho, launched in 1860. &&&&&&&&&&017890.&&&&&017,890 &&&&&&&&&&&08485.&&&&&08,485 sq mi
(&&&&&&&&&&021976.&&&&&021,976 km2)
State map highlighting Idaho County
Jefferson County 051 Rigby 1913 Fremont County 1J Named for Thomas Jefferson, the third President of the United States. &&&&&&&&&&034198.&&&&&034,198 &&&&&&&&&&&01095.&&&&&01,095 sq mi
(&&&&&&&&&&&02836.&&&&&02,836 km2)
State map highlighting Jefferson County
Jerome County 053 Jerome 1919 Gooding and Lincoln Counties 2J Named for Jerome Hill, his son-in-law Jerome Kuhn, or his grandson Jerome Kuhn, Jr. &&&&&&&&&&025479.&&&&&025,479 &&&&&&&&&&&&0600.&&&&&0600 sq mi
(&&&&&&&&&&&01554.&&&&&01,554 km2)
State map highlighting Jerome County
Kootenai County 055 Coeur d'Alene 1864 Nez Perce County K Named for the Kootenai Native American tribe. &&&&&&&&&0185010.&&&&&0185,010 &&&&&&&&&&&01245.&&&&&01,245 sq mi
(&&&&&&&&&&&03225.&&&&&03,225 km2)
State map highlighting Kootenai County
Latah County 057 Moscow 1888 Nez Perce County 1L Named for Latah Creek, which means "the place of pine trees and sestle" in Nez Perce. &&&&&&&&&&041301.&&&&&041,301 &&&&&&&&&&&01077.&&&&&01,077 sq mi
(&&&&&&&&&&&02789.&&&&&02,789 km2)
State map highlighting Latah County
Lemhi County 059 Salmon 1869 Idaho County 2L Named for Limhi, a king mentioned in the Book of Mormon. &&&&&&&&&&&08441.&&&&&08,441 &&&&&&&&&&&04564.&&&&&04,564 sq mi
(&&&&&&&&&&011821.&&&&&011,821 km2)
State map highlighting Lemhi County
Lewis County 061 Nezperce 1911 Nez Perce County 3L Named for Meriwether Lewis, a leader of the Lewis and Clark Expedition. &&&&&&&&&&&03739.&&&&&03,739 &&&&&&&&&&&&0479.&&&&&0479 sq mi
(&&&&&&&&&&&01241.&&&&&01,241 km2)
State map highlighting Lewis County
Lincoln County 063 Shoshone 1895 Blaine County 4L Named for Abraham Lincoln, the sixteenth President of the United States. &&&&&&&&&&&05450.&&&&&05,450 &&&&&&&&&&&01206.&&&&&01,206 sq mi
(&&&&&&&&&&&03124.&&&&&03,124 km2)
State map highlighting Lincoln County
Madison County 065 Rexburg 1913 Fremont County 1M Named for James Madison, the fourth President of the United States. &&&&&&&&&&054547.&&&&&054,547 &&&&&&&&&&&&0472.&&&&&0472 sq mi
(&&&&&&&&&&&01222.&&&&&01,222 km2)
State map highlighting Madison County
Minidoka County 067 Rupert 1913 Lincoln County 2M Its name comes from Native American languages, meaning "a fountain or spring of water" or "broad expanse." &&&&&&&&&&022480.&&&&&022,480 &&&&&&&&&&&&0760.&&&&&0760 sq mi
(&&&&&&&&&&&01968.&&&&&01,968 km2)
State map highlighting Minidoka County
Nez Perce County 069 Lewiston 1864 original county N Named for the Nez Perce, a Native American tribe. &&&&&&&&&&042987.&&&&&042,987 &&&&&&&&&&&&0849.&&&&&0849 sq mi
(&&&&&&&&&&&02199.&&&&&02,199 km2)
State map highlighting Nez Perce County
Oneida County 071 Malad City 1864 original county 1O Named for Oneida Lake in New York, where many early settlers came from. &&&&&&&&&&&04953.&&&&&04,953 &&&&&&&&&&&01200.&&&&&01,200 sq mi
(&&&&&&&&&&&03108.&&&&&03,108 km2)
State map highlighting Oneida County
Owyhee County 073 Murphy 1863 original county 2O An old spelling of Hawaii. Hawaiian fur trappers explored this area in the early 1800s. &&&&&&&&&&012722.&&&&&012,722 &&&&&&&&&&&07678.&&&&&07,678 sq mi
(&&&&&&&&&&019886.&&&&&019,886 km2)
State map highlighting Owyhee County
Payette County 075 Payette 1917 Canyon County 1P Named for Francois Payette, a Canadian-born fur trader and early settler. &&&&&&&&&&027279.&&&&&027,279 &&&&&&&&&&&&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 Named for the American Falls Power Plant. &&&&&&&&&&&08253.&&&&&08,253 &&&&&&&&&&&01406.&&&&&01,406 sq mi
(&&&&&&&&&&&03642.&&&&&03,642 km2)
State map highlighting Power County
Shoshone County 079 Wallace 1864 original county S Named for the Shoshone Native American tribe. &&&&&&&&&&014026.&&&&&014,026 &&&&&&&&&&&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 Named for the Teton Range mountains in Wyoming. &&&&&&&&&&012549.&&&&&012,549 &&&&&&&&&&&&0450.&&&&&0450 sq mi
(&&&&&&&&&&&01165.&&&&&01,165 km2)
State map highlighting Teton County
Twin Falls County 083 Twin Falls 1907 Cassia County 2T Named for the Twin Falls waterfall on the Snake River. &&&&&&&&&&095156.&&&&&095,156 &&&&&&&&&&&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 Named for the Long Valley located in the county. &&&&&&&&&&012644.&&&&&012,644 &&&&&&&&&&&03733.&&&&&03,733 sq mi
(&&&&&&&&&&&09668.&&&&&09,668 km2)
State map highlighting Valley County
Washington County 087 Weiser 1879 Ada County W Named for George Washington, the first President of the United States. &&&&&&&&&&011425.&&&&&011,425 &&&&&&&&&&&01456.&&&&&01,456 sq mi
(&&&&&&&&&&&03771.&&&&&03,771 km2)
State map highlighting Washington County

Counties That No Longer Exist

Over time, some counties were created and then later combined or changed. Here are two counties that no longer exist in Idaho:

See also

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