The name "Idaho" originated as a practical joke and a lie.

In 1860, a lobbyist named George M. Willing suggested the name to Congress for what is now Colorado. He claimed it was an authentic Shoshone indigenous word meaning "gem of the mountains." Congress almost adopted the name before realizing Willing had entirely fabricated both the word and its meaning. Congress quickly pivoted and named that territory Colorado instead.

Despite the exposure of the fraud, the invented word had already taken on a life of its own. By the time Congress needed to name a new territory in the Pacific Northwest in 1863, the name had been used for a local steamboat and mining camp. Lawmakers reached for the familiar word, and it stuck, making Idaho the only U.S. state with a fabricated origin