Humans are known to have inhabited Idaho for at least 14,500 years. Ancient artifacts that have been found in the area, are among the oldest known artifacts in North America.

Until 1846, Idaho was part of the Oregon Country claimed by both the United States and UK. The US gained undisputed control over Oregon in 1846.

Parts of present day Idaho were initially divided between the Oregon, Washington and Dakota Territories, but in 1863 the Idaho Territory was created. The Idaho Territory included most of the present day states of Idaho, Montana and Wyoming.

One interesting act about Idaho is it is the only state named as a result of a hoax. In the early 1860s, when a new territory was being organized in the Rocky Mountains, lobbyist George M. Willing suggested the name "Idaho" which he claimed meant "the sun comes from the mountains" or "gem of the mountains" in the Shoshone Indian language. Congress however rejected Willing's suggestion, and this new territory was named the Colorado Territory. However, in the meantime, the name "Idaho" had gained currency, even though Willing had subsequently admitted to making up the name. A Columbia River steamship was named "Idaho", and Idaho County was created in the East of the Washington Territory. And, as previously described, in 1863, the Idaho Territory (which included Idaho County) was created from a portion of the Washington Territory.

In the period following the American Civil War (1861 to 1865), Idaho became an important mining state, at one time even producing almost a fifth of the gold mined in the United States. Mining however was not without incident, and the state was plagued by frequent labor unrest, indeed, during one strike in 1892, a shooting war even developed between striking miners and company guards.

Idaho was also an important location in the Progressive political movement, adopting policies such as woman's suffrage (1896) and prohibition (1916) in advance of other parts of the country. It was during this period that the state's economy gradually moved away from mining towards agriculture. Some mining towns became deserted "ghost towns", and others transformed themselves into ski resorts.

In the post World War II period, mining was remained an important industry in Idaho. In recent years, the state was unfortunately gained a certain noteriety in certain sections of the press, because of the presence of certain extreme rightwing and survivalist groups in some parts of the state - however the vast majority of Idaho residents are opposed to such ideologies.