6 of 13 Flora and Fauna: 1 | 2 | 3 | 4 | 5 Letters and Records: 1 | 2 Maps: 1 | 2 | 3 Native Americans: 1 | 2 | 3 MISSOURI HISTORICAL SOCIETY JEFFERSON'S CORRESPONDENCE This letter from Thomas Jefferson, dated July 6, 1803, authorized the party's excursion to the West. Jefferson had given Lewis the mission "to find the most direct and practicable water route across the continent."

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