December 16, 1800 | Letter Thomas Jefferson to Caspar Wistar, December 16, 1800 Thomas Jefferson introduces Caspar Wistar to the work of William Dunbar, excited at the prospect of a scientific correspondent "on the very verge of the great terra incognita of our western continent."
December 16, 1800 | Letter Thomas Jefferson to Caspar Wistar, December 16, 1800 In a personal addition to his other letter of December 16, 1800, Thomas Jefferson assures Caspar Wistar of William Dunbar's fitness for membership in the American Philosophical Society.
January 12, 1801 | Letter Thomas Jefferson to William Dunbar, January 12, 1801 Thomas Jefferson acknowledges William Dunbar's July 14, 1800 letter and enclosures; he also touches on other scientific matters and expresses his satisfaction at having a scientific correspondent on the western edge of the country.
March 20, 1801 | Letter Thomas Jefferson to Joseph-Mathias Gerard de Rayneval, March 20, 1801 Thomas Jefferson addresses the history and purposes of the Ohio, Wabash, and Loyal Land Companies in this letter about Conrad Alexandre Gérard de Rayneval's financial difficulties with the Wabash Company. State cession of lands to the companies are germane to the discussion.
July 13, 1801 | Letter Thomas Jefferson to William C. C. Claiborne, July 13, 1801 Thomas Jefferson writes to William Claiborne with news of his appointment as Governor of Mississippi, noting the importance of the region as "the principal point of contact between Spain and us, & also as it is the embryo of a very great state." Jefferson also warns Claiborne of the importance of encouraging the residents of Mississippi to embrace party politics similar to his.
April 18, 1802 | Letter Thomas Jefferson to Robert Livingston, April 18, 1802 Thomas Jefferson sends a cipher to Robert Livingston, as well as his musings on the cession of Louisiana.
March 3, 1803 | Letter Thomas Jefferson to William Dunbar, March 3, 1803 After thanking William Dunbar for earlier correspondence, including Martin Duralde's report to the American Philosophical Society, Thomas Jefferson expresses hopes that American rights to the Mississippi River can be maintained without war; the President also anticipates the acquisition of Native lands on the left bank of the river to "plant on the Missisipi itself the means of it's own defence."
March 14, 1803 | Letter Albert Gallatin to Thomas Jefferson, March 14, 1803 Albert Gallatin informs Thomas Jefferson of the preparations he has made for the Corps of Discovery expedition, including commissioning Nicholas King's blank projection of western North America. Gallatin demonstrates his familiarity with the work of cartographers including Arrowsmith, Delisle, and Mackenzie, assuming Jefferson has the same background knowledge.
April 17, 1803 | Letter Levi Lincoln to Thomas Jefferson, April 17, 1803 Levi Lincoln offers suggestions for the Corps of Discovery's trip and warns Thomas Jefferson of strong objections from the opposition.
April 23, 1803 | Letter Thomas Jefferson to Meriwether Lewis, April 23, 1803 Thomas Jefferson worries that lengthy preparations are keeping Meriwether Lewis from a swift departure, fearing a delay to the expedition.
January 22, 1804 | Letter Thomas Jefferson to Meriwether Lewis, January 22, 1804 Thomas Jefferson informs Meriwether Lewis of the steps the United States is taking to consolidate its position in the land along the Mississippi.
March 13, 1804 | Letter Thomas Jefferson to William Dunbar, March 13, 1804 Thomas Jefferson thanks William Dunbar for his letter of January 28, promising to forward his paper on the Mississippi River to the American Philosophical Society. Jefferson then writes a detailed discussion of the science of water in a river like the Mississippi. Jefferson also relates his plans for directing surveying parties to the Mississippi and Ohio Rivers, in addition to explorations of the Red and other more southern waterways. Jefferson concludes with speculations on the future of the Lousiana Territory.