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