1804
May -Embarkation from St. Louis for voyage up
the Missouri
August-Death of Sergeant Charles Floyd, the only member of the Corps to die on the expedition; first council with Indians (Missouri and Oto tribes)
September-Council with Teton Sioux
October-Establishment of winter quarters, Fort Mandan, in what is now North Dakota

1805
April-Departure from Fort Mandan with interpreters Toussaint Charbonneau and wife
Sacagawea
June-Month-long, eighteen-mile portage around Great Falls (Montana)
August-Crossing of the Great Divide; council with the Shoshones
October-Arrival at the Columbia River
November-First view of Pacific estuary
December-Establishment of winter quarters, Fort Clatsop (Oregon)

1806
March-Departure from Fort Clatsop for journey east
July-Division of the party: Lewis explores the Marias River to the north of the Missouri, Clark travels east on the Yellowstone; Lewis’s party engages in fight with Blackfeet Indians
August-Reunion at the confluence of the Missouri and Yellowstone; farewell to Sacagawea at Mandan and Hidatsa villages
September-Return to St. Louis