National Idaho Day is observed worldwide every May 17 to celebrate Idaho as the 43rd state to join the United States. Established by National Day Calendar as part of its National State Days project, this day recognizes Idaho's rich natural resources and its nickname, the Gem State, due to its production of over 70 varieties of precious and semi-precious stones, including the state gemstone, star garnet. Idaho is also known as the Potato State, reflecting its status as the leading producer of potatoes in the U.S. The state's history includes habitation by Native tribes such as the Nez Perce and Coeur d’Alene, and it was explored by the Lewis and Clark expedition in 1805. Idaho became a territory in 1862 and achieved statehood in 1890. National Idaho Day does not coincide with the actual anniversary of Idaho's statehood but is part of a broader celebration of all U.S. states in the order they joined the Union.