1804...Under order of President Thomas Jefferson, the Lewis & Clark Expedition departs from St. Louis, Missouri, on May 14, to chart a course to the Pacific Ocean.
1841...First emigrant wagon train for California. Forty-seven people leave Independence Missouri, on May 1 and reach California on November 4.
1842...Settlement of Oregon begins via the Oregon Trail.
1847...After violent clashes with settlers over polygamy, Mormons leave Nauvoo, Illinois, and head for the west under Brigham...