1803: The US buys the Louisiana territories, which includes parts of modern-day Idaho.
1805: Lewis and Clark enter what is now Idaho at Lemhi pass and cross the Bitterroot Mountains with help from the Nez Perce Indians.
1810: Fort Henry is built. It is the first fur post west of the Rocky Mountains.
1822: William Ashley organizes the Rocky Mountain Fur Company.
1834: Forts Laramie, Boise and Hall are created as supply posts serving westward-bound explorers.
1836: Henry H. Spalding creates Idaho’s first school, first irrigation system and plants first potatoes.
1843: First Oregon trail wagons cross Idaho.
1848-1853: Cataldo Mission, Idaho’s oldest building, is constructed at Coeur D’ Alene by Catholic Missionaries.
1860: Franklin is founded as the first town in Idaho by Mormons who thought they were in Utah Territory.
1863: President Lincoln signs an act creating the Idaho Territory from parts of the Washington and Dakota Territories
1864: Boise is incorporated as a city and becomes the capital of the Idaho Territory.
1890: President Benjamin Harrison admits Idaho as the 43rd state.
1905: The completion of Milner Dam on the Snake River gives rise to many agricultural communities in southern Idaho such as Nampa and Twin Falls.
1920: State Capitol building is completed
1930-1940: Basque immigrants (French and Spanish descent) settle in Boise, making it one of the largest centers of Basque culture in America.
1936: Sun Valley Ski resort opens.