Idaho became a state on July 3, 1890. Idaho is the 43rd state. It became a state when Great Britain and America signed a treaty. The first people to settle in Idaho were the Nezperce, Shoshone, and the Blackfeet Indians. Through the 1800s more settlers came to Idaho. Many settlers traveled along the Oregon Trail which went through southern Idaho. In 1805 Lewis and Clark entered Idaho heading for the Pacific Ocean.