On July 3, 1890, the Idaho Territory became the 43rd state
in the Union..

Exploration of the North American continent mostly proceeded
inward from the Atlantic and Pacific coasts and northward from
Spanish Mexico. Therefore, the rugged territory that would
become Idaho long remained untouched by Spanish, French,
British and American trappers and explorers. Even as late as
1805, Idaho Native Americans like the Shoshone had never
encountered Europeans.