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The Corps of Discovery leaves Camp Wood and begins its journey up the Missouri River "under a gentle breeze
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The Corps holds the first Independence Day celebration west of the Mississippi River
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North of present-day Omaha, Nebraska, the Corps holds a council with the Oto and Missouri Indians
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Sergeant Charles Floyd dies of natural causes near present-day Sioux City, Iowa; he will be the only fatality among the Corps of Discovery during the expedition
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The Corps holds a council with the Yankton Sioux at present-day Yankton, South Dakota
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The Corps enters the Great Plains and sees animals unknown in the eastern United States.
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The Corps has a tense encounter with the Teton Sioux near today's Pierre, South Dakota; one of the Sioux chiefs waves his men off and conflict is averted.
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Near today's Bismarck, North Dakota, the Corps arrives at the villages of the Mandan and Hidatsa, buffalo-hunting tribes that live along the Missouri River.
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Lewis and Clark hire French-Canadian fur-trader Toussaint Charbonneau and his Shoshone wife, Sacagawea, to act as interpreters on the journey ahead.
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The men record the temperature at 45 degrees below zero, "colder than [they] ever knew it to be in the States.
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The men finish building Fort Mandan, their winter quarters in present-day North Dakota
