Idaho

Native Americans have lived in the region for at least 10,000 years. Groups in the north included the Kutenai, Kalispel, Coeur d’Alene and Nez Percé; the Northern Paiute lived in the west-central region, and the western and northern Shoshone occupied the south. About 8,000 Native Americans lived in the region in 1805.⁠[1]

In 1805 the expedition led by Meriwether Lewis and William Clark entered present-day Idaho at Lemhi Pass and crossed the Bitterroot Range by way of Lolo Pass, becoming the first white men to explore the region.⁠[1][2]

For more than fifty years afterward, the only white residents of the Idaho wilderness were a few fur traders and missionaries.⁠[3]

In 1834 the Hudson’s Bay Company built Fort Boise and Nathaniel Wyeth built Fort Hall; the Hudson’s Bay Company bought Fort Hall in 1836. Both posts became stopping points on the Oregon Trail.⁠[1]

In 1836 Henry Spalding founded a mission on Lapwai Creek near Lewiston; its school, opened in 1837 for Native American children, was the first in the area. Irrigated farming in Idaho dates from 1839 at Spalding’s Nez Perce mission.⁠[1][3]

The region was part of the disputed Oregon Country, which passed to the United States when Britain relinquished its claims by treaty in 1846. The northern boundary with British Columbia follows the 49th parallel under the 1846 treaty, and the southern boundary follows the 42nd parallel under the 1819 treaty with Spain.⁠[4][5]

Mormon colonists founded Franklin on April 14, 1860, and it had the earliest school for white children in the area. That fall, prospector E. D. Pierce’s party found gold in the Clearwater country, and the town of Pierce was established in December.⁠[6][1][3]

Gold was discovered in the Boise Basin in the summer of 1862. That fall the mining towns of Placerville, Centerville, West Bannock (later Idaho City) and Hog’em (Pioneer City) were founded, becoming major mining centers in 1863, by which time 8,000 to 10,000 men had arrived in the basin.⁠[7][6]

In the spring of 1863 strikes followed at Rocky Bar (the South Boise mines), Silver City (the Owyhee mines, May 18) and Virginia City (May 26, later part of MontanaMontanaMontana is a state in the northwestern United States, with the Rocky Mountains in the west and the Great Plains in the east; its capital is Helena and its largest city is Billings. Montana became the 41st U.S. state on November 8, 1889, and the 2020 census (April 1, 2020) counted 1,084,225 residents.Open the full entry).⁠[6]

On March 4, 1863, President Abraham LincolnAbraham LincolnAbraham Lincoln (February 12, 1809 – April 15, 1865) was the 16th president of the United States (1861–1865). Born to a frontier farming family in Kentucky, he had less than a year of formal schooling, taught himself law, and served in the Illinois legislature and the U.S. House of Representatives before winning the presidency as the Republican candidate in 1860. During the Civil War he preserved the Union, issued the Emancipation Proclamation in 1863 and pushed the Thirteenth Amendment abolishing slavery through Congress. He was shot by John Wilkes Booth at Ford’s Theatre in Washington on April 14, 1865, and died the next day.Open the full entry signed the act creating Idaho Territory. The territory at first included all of present-day Montana and nearly all of WyomingWyomingWyoming is a U.S. state, the ninth largest by area, with its capital at Cheyenne. Wyoming was admitted to the Union on July 10, 1890, as the 44th state, and the 2020 census (April 1, 2020) counted 576,851 residents.Open the full entry, an area one-quarter larger than TexasTexasTexas is a U.S. state in the south-central United States, with its capital at Austin and its largest city Houston. It was admitted to the Union on December 29, 1845, as the 28th state, and the 2020 census (April 1, 2020) counted 29,145,505 residents.Open the full entry.⁠[8][6][2]

The first territorial governor, William Henson Wallace, organized the territory at Lewiston on July 10, 1863. A census that September counted 32,342 residents, including more than 16,000 in Boise County and nearly 12,000 in what became Montana. The first territorial legislature met at Lewiston on December 7, 1863.⁠[6]

On June 9, 1863, some Nez Perce bands agreed to a treaty that greatly reduced the size of their reservation.⁠[6]

Montana Territory was created from northeastern Idaho on May 26, 1864, and Wyoming Territory followed in 1868, bringing Idaho Territory close to its present shape.⁠[6][3]

Throughout 1864 Lewiston served as the temporary seat of territorial government, but there was no permanent capital. At the second legislative session, held in Lewiston in November 1864, northern members proposed a new territory combining northern Idaho with eastern Washington Territory, but southern legislators, who held the majority, defeated the plan. The legislature then passed an act making Boise the capital, effective December 24, 1864. The northern population was 2,790 and the southern 18,997. Boise City was incorporated the same year and became the seat of Ada County.⁠[7][2][9]

Lewiston lawyers sued on the grounds that the session had met on the wrong day, and Lewiston placed an armed guard over the territorial papers. Territorial secretary and acting governor C. DeWitt Smith arrived in Lewiston on March 2, 1865, and with federal troops from Fort Lapwai took the seal and many papers to Boise, arriving on April 14. The territorial supreme court later upheld the legality of the second session, confirming Boise as capital from December 24, 1864.⁠[7]

C. DeWitt Smith died suddenly at Rocky Bar on August 19, 1865, and H. C. Gilson, a bartender, obtained a commission as secretary and took over; in April 1866 Gilson disappeared with the territorial treasury, and Governor Caleb Lyon was driven out over his unpopular Indian policy, leaving Idaho again without a functioning territorial government. In the summer of 1866 D. W. Ballard became governor, the government became permanent, and the territorial supreme court was organized.⁠[10]

By 1869 placer mining was increasingly dominated by Chinese miners, and the census of 1870 recorded 3,853 of Idaho’s 6,572 miners as Asian.⁠[3]

In 1877 forces under General Oliver O. Howard defeated the Nez Percé led by Chief Joseph, and the tribe was sent to a reservation in present-day OklahomaOklahomaOklahoma is a U.S. state whose capital is Oklahoma City. It was admitted to the Union on November 16, 1907, as the 46th state, and its population in the 2020 census (April 1, 2020) was 3,959,353.Open the full entry. Indian wars from 1877 to 1879 further disrupted the territory’s progress.⁠[1][3][2]

A rush to the Wood River country was under way by 1880. In 1882 the Northern Pacific Railroad was completed in Idaho and construction began on the New York Canal; railroad construction in the territory was completed by 1884, reviving mining and towns. By 1884 the Coeur d’Alene region showed promise as a lead-silver-zinc district. The Territorial Capitol was completed in 1886.⁠[3][2]

North Idaho sought to join Washington Territory, and a measure to annex it had passed Congress by March 2, 1887; Governor E. A. Stevenson appealed to President Grover Cleveland, which delayed the breakup. NevadaNevadaNevada is a state in the western United States bordered by Oregon, Idaho, Utah, Arizona, and California; its capital is Carson City. It was admitted to the Union on October 31, 1864, as the 36th state, and its population in the 2020 census (April 1, 2020) was 3,104,614.Open the full entry also sought much of southern Idaho. A congressional decision on February 29, 1888, preserved the territory’s boundaries and cleared the way for statehood.⁠[3][11]

On April 2, 1889, Governor E. A. Stevenson, on the explicit advice of two U.S. senators, called a constitutional convention on his own initiative; the territorial legislature had not authorized it, and there were no funds for electing delegates or holding a ratification vote. His successor, George L. Shoup, reissued the call and allowed other methods of choosing delegates: ten counties used party committees, six used county conventions, and Owyhee and Custer counties held popular elections.⁠[11]

Voters approved the constitution by an overwhelming margin on November 5, 1889. Mormons could not vote at the time, and the constitution was designed to prevent their future voting.⁠[11]

President Benjamin Harrison signed the admission bill at 10 a.m. on July 3, 1890, and Idaho became a state under its 1889 constitution.⁠[8][3][11]

Mine-labor wars broke out in the Coeur d’Alene region between 1892 and 1899. In 1892 martial law was declared and federal troops broke up strikes, and in 1899 Governor Frank Steunenberg again brought in federal troops to maintain order. Six years later the former governor was assassinated. Labor protests involving the Industrial Workers of the World erupted frequently between 1890 and 1910.⁠[12][1][4]

The Carey Act of 1894 spurred the expansion of irrigation, and major projects arose around Twin Falls early in the twentieth century. Swan Falls hydroelectric dam was completed in 1901. After the Reclamation Act of 1902, dams and reservoirs were built at Arrowrock (1915), American Falls (1927), Deadwood (1929), Cascade (1948), Anderson Ranch (1950) and Palisades (1958).⁠[12][2]

Women gained the right to vote in Idaho in 1896, making it one of the first states to extend suffrage to women.⁠[13]

Lumber operators from the western Great Lakes states began moving into North Idaho in 1900, and within a few years logging rivaled farming in economic importance. In 1910 the North Idaho fires known as “The Big Blowup” burned the region.⁠[12][2]

In 1936 the Union PacificUnion PacificUnion Pacific Corporation is an Omaha-based U.S. railroad holding company whose Union Pacific Railroad runs freight trains in 23 western states. In 2025 it agreed to merge with Norfolk Southern.Open the full entry railroad developed Sun Valley, the first major ski resort in the United States, and the first ski chair lift went into operation that year.⁠[1][2]

The first Albertsons store opened in 1939, and in 1941 J. R. Simplot began a potato dehydration operation. Legislation in 1947 reduced the number of public school districts from more than 1,100 to fewer than 115.⁠[2][1]

In 1951 the EBR-I experimental reactor near Idaho Falls, at the site of today’s Idaho National Laboratory, first produced atomic power, beginning noncommercial use of nuclear energy there.⁠[2][1]

The Sawtooth National Recreation Area was completed in 1972, the Port of Lewiston opened in 1975, and the Teton Dam collapsed in 1976.⁠[2]

Floods in North Idaho in 1995 brought the U.S. president to the state, and in 2009 Idaho hosted the Special Olympics World Winter Games.⁠[2]

On April 26, 2021, the U.S. Census Bureau released the 2020 census apportionment results. Idaho was apportioned 2 seats in the U.S. House of Representatives, the same as after the 2010 census, with an average of 920,689 people per seat, giving it 4 electoral votes in the 2024 and 2028 presidential elections.⁠[14][15][16]

Idaho still operates under its original constitution of 1889, a detailed document amended more than 100 times that establishes separate executive, legislative and judicial branches and limits the governor’s powers. The governor and six other elected executive officers serve four-year terms. The legislature is bicameral, consisting of a Senate and a House of Representatives; it meets annually, and members of both chambers serve two-year terms. The judiciary comprises the Supreme Court, a court of appeals, seven district courts and county magistrate courts; the Supreme Court has five justices. The state has more than 1,000 units of local government, including counties, municipalities and school districts.⁠[13][5][1]

The Idaho Legislature has 35 senators and 70 representatives; the state is divided into 35 legislative districts, each electing one senator and two representatives. The Legislature convenes each year on the Monday on or closest to January 9 and sits for about three months.⁠[17]

As of November 2026 the governor is Brad Little, who has served as Idaho’s 33rd governor since January 7, 2019; he was elected in November 2018 and reelected in November 2022. He previously served as the 37th lieutenant governor from January 6, 2009, and entered the state Senate in 2001.⁠[18]

Idaho borders the Canadian province of British Columbia to the north, Montana (along the Continental Divide) and Wyoming (including a small slice of Yellowstone National Park) to the east, UtahUtahUtah is a U.S. state bordered by Idaho to the north, Wyoming to the northeast, Colorado to the east, Arizona to the south and Nevada to the west, with its capital at Salt Lake City. It was admitted to the Union on January 4, 1896, as the 45th state, and the 2020 census (April 1, 2020) counted 3,271,616 residents.Open the full entry and Nevada to the south, and OregonOregonOregon (officially the State of Oregon) is a state on the Pacific coast of the western United States; its capital is Salem and its largest city is Portland. It was admitted to the Union on February 14, 1859, as the 33rd state. Its population in the 2020 census (April 1, 2020) was 4,237,256.Open the full entry and Washington StateWashington (state)Washington is a state on the Pacific coast of the northwestern United States; its capital is Olympia and its largest city is Seattle. Washington was admitted to the Union on November 11, 1889, as the 42nd state, and the 2020 census (April 1, 2020) counted 7,705,281 residents.Open the full entry to the west. The 480-mile (770-kilometre) Oregon boundary is a straight line except between Weiser and Lewiston, where Hells Canyon of the Snake River forms the border.⁠[5]

In the Census Bureau’s state area measurements (boundaries as of January 1, 2010), Idaho has a total area of 83,569 square miles (216,443 square kilometres), of which 82,643 square miles (214,045 square kilometres) is land and 926 square miles (2,398 square kilometres) is water, all of it inland water. It ranks 14th among the states in total area.⁠[19][5]

The highest point is Borah Peak in the Lost River Range in Custer County, at 12,662 feet (3,859 metres); the lowest point is on the Snake River at Lewiston. The state is 479 miles long and 305 miles wide at its widest, and its geographic center is at the settlement of Custer on the Yankee Fork River in Custer County. Idaho has more than 2,000 lakes, the largest being Lake Pend Oreille at 180 square miles. The Snake River, flowing east to west across southern and western Idaho, is the state’s major natural feature and holds most of its irrigated farmland; Hells Canyon, 7,900 feet (2,400 metres) deep, is North America’s deepest gorge. Shoshone Falls drops 212 feet (65 metres), and the state contains Craters of the Moon National Monument.⁠[8][5]

Elevation influences the climate more than latitude, and prevailing westerly winds from the Pacific affect most of the state. Most of the Snake River Plain receives less than 10 inches (250 millimetres) of precipitation a year, while parts of the Northern Rockies receive more than 50 inches (1,250 millimetres); the southeastern counties have a drier, colder continental climate. The recorded temperature extremes are 118 °F at Orofino on July 28, 1934, and −60 °F at Island Park Dam on January 18, 1943. The state lies in the Pacific and Mountain time zones.⁠[5][8][20]

Evergreen forests cover nearly two-fifths of the state, and the Frank Church River of No Return, Selway-Bitterroot and Gospel Hump wilderness areas together form the largest contiguous wilderness in the conterminous 48 states.⁠[5]

The 2010 census (April 1, 2010) counted 1,567,582 people in Idaho. The Census Bureau’s Vintage 2025 estimate put the population at 2,029,733 on July 1, 2025, up 10.4% from the April 1, 2020, estimates base of 1,839,123; population density in 2020 was 22.3 people per square mile.⁠[21]

In American Community Survey data for 2020–2024, Idaho had 713,005 households; 5.9% of residents were foreign-born, 31.8% of people aged 25 and older held a bachelor’s degree or higher, and median household income was $77,800 (in 2024 dollars).⁠[21]

More than nine-tenths of residents are of European descent and Hispanics make up almost one-tenth, with smaller numbers of Native Americans, Asians and African Americans. Nearly half of the population are church members, about one-third of them Mormon, followed by Roman Catholics, Methodists and Presbyterians. The population is slightly younger than the national average; more than half live in urban areas, concentrated most heavily around Boise, Nampa and Meridian, and California is the largest source of new residents.⁠[5]

U.S. Bureau of Economic Analysis data put Idaho’s nominal gross domestic product (all industry total) at $137,401.9 million in 2025, up from $129,692.6 million in 2024 and $121,697.5 million in 2023.⁠[22]

Idaho grows about one-third of U.S. potatoes; other farm products include dairy goods, cattle, hay, sugar beets, wheat, lentils, barley and alfalfa seed. About half of the farmland is irrigated, served by some 15,000 miles (24,140 kilometres) of canals. The main commercial trees are Douglas fir, ponderosa pine and western white pine, the chief metal products are molybdenum, silver and lead, and phosphate mining is important in the southeast.⁠[5][1]

Manufacturing exceeds agriculture in value added and centers on processing food, forest and mineral products, along with electronics, industrial machinery and printing. Hydroelectric power, mainly from stations on the Snake River, supplies virtually all of the state’s energy needs, and Idaho National Laboratory near Arco is a federal nuclear research site. Sun Valley is a major winter sports destination; more than one-fourth of the workforce is employed in services, and government is the second-largest source of income. The constitution limits general-obligation debt to $2 million.⁠[5][1]

State institutions of higher education include the University of Idaho in Moscow (founded 1889, the land-grant university), Idaho State University in Pocatello (1901), Boise State University (1932) and Lewis-Clark State College in Lewiston; community colleges include North Idaho College in Coeur d’Alene and the College of Southern Idaho in Twin Falls. Private institutions include the College of Idaho in Caldwell (1891), Northwest Nazarene University in Nampa (1913) and Brigham Young University–Idaho in Rexburg.⁠[5][1]

The name is thought to derive from a Shoshone phrase meaning “gem of the mountains.” The state’s nickname is the Gem State; it is also called the Gem of the Mountains and the Panhandle State.⁠[5][1][8]

The state motto is the Latin “Esto Perpetua,” which the state renders as “Be Eternal”; it appears on the state seal. The seal was designed in 1891 by Emma Edwards Green, the only state seal designed by a woman, and was adopted by the legislature on March 14, 1891.⁠[23][8]

The state flag, adopted in 1907, has a blue field bearing the state seal above a red-and-gold band inscribed “State of Idaho.”⁠[23]

The state bird (mountain bluebird), state flower (syringa) and state song (“Here We Have Idaho”) date from 1931; the state tree (western white pine) from 1935, the state gem (star garnet) from 1967, the state horse (Appaloosa) from 1975, the state fossil (Hagerman Horse) from 1988, the state fish (cutthroat trout) from 1990, the state fruit (huckleberry) from 2000, the state vegetable (potato) from 2002 and the state raptor (peregrine falcon) from 2004.⁠[8]

State of Idaho: Official website: https://idaho.gov/ (opens in a new window).⁠[24]

Office of the Governor: Official website: https://gov.idaho.gov/ (opens in a new window).⁠[25]

Idaho State Legislature: Official website: https://legislature.idaho.gov/ (opens in a new window).⁠[17]

Idaho Capitol Commission: Official website: https://capitolcommission.idaho.gov/ (opens in a new window).⁠[26]