February 27, 1803 | Letter Thomas Jefferson to Benjamin Smith Barton, February 27, 1803 Thomas Jefferson informs Benjamin Smith Barton of Meriwether Lewis' upcoming journey, excited at the prospect of the scientific advances that will result.
February 28, 1803 | Letter Thomas Jefferson to Benjamin Rush, February 28, 1803 Thomas Jefferson informs Benjamin Rush of Meriwether Lewis' upcoming trip west, asking Rush to assist Lewis in any way possible. Jefferson then details his ongoing digestive problems.
March 2, 1803 | Letter Thomas Jefferson to Robert Patterson, March 2, 1803 Thomas Jefferson writes to Robert Patterson of the planned expedition west, asking him to help prepare Meriwether Lewis for taking geographical measurements.
March 6, 1803 | Letter Andrew Ellicott to Thomas Jefferson, March 6, 1803 Andrew Ellicott writes of his willingness to train Meriwether Lewis in taking measurements on his trip westward.
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.
March 15, 1803 | Letter Robert Patterson to Thomas Jefferson, March 15, 1803 Robert Patterson explains the mathematical formulas he will show Meriwether Lewis in preparing him for his journey. Please note, the complex nature of the formulas and examples makes it more feasible to leave them off of the transcribed document than include them; see the images for a complete rendition of Patterson's work.
April 3, 1803 | Letter Meriwether Lewis to Thomas Jefferson, April 3, 1803 Meriwether Lewis writes to Jefferson regarding his preparations, including his many communications with men of science. Lewis includes his plans for a collapsible boat.
April 13, 1803 | Letter Albert Gallatin to Thomas Jefferson, April 13, 1803 Albert Gallatin responds to Jefferson's planned instructions to Lewis by stressing the importance of evaluating the suitability of the parts of the trans-Missouri region not included in the Louisiana Purchase. He wonders if British appropriation of the region is a possibility.
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 22, 1803 | Letter From Thomas Jefferson to Lewis Harvie, April 22, 1803 Thomas Jefferson writes to Lewis Harvie, informing him of Meriwether Lewis' progress in preparing for his expedition. Jefferson also reassures Harvie that questions between Spain and France over the Louisiana Territory will not interfere with the United States' acquisition of the region.
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.
April 27, 1803 | Letter Thomas Jefferson to Meriwether Lewis, April 27, 1803 Thomas Jefferson informs Meriwether Lewis he will be forwarding copies of his instructions for the journey into the Louisiana Territory. The instructions may be shown to members of the American Philosophical Society, in case they would make any modifications.
April 30, 1803 | Letter Thomas Jefferson to Meriwether Lewis, April 30, 1803 Thomas Jefferson encourages Meriwether Lewis to follow Andrew Ellicott's advice on scientific matters involving astronomical measurements.
June 11, 1803 | Letter Benjamin Rush to Meriwether Lewis, June 11, 1803 Benjamin Rush writes instructions for Meriwether Lewis, who is about to undertake his trip westward.
June 20, 1803 | Letter Thomas Jefferson to Meriwether Lewis, June 20, 1803 Thomas Jefferson issues detailed instructions to Meriwether Lewis, addressing every aspect of the upcoming expedition.
September 8, 1803 | Letter Meriwether Lewis to Thomas Jefferson, September 8, 1803 Meriwether Lewis updates Thomas Jefferson on his progress preparing for the westward expedition.
October 3, 1803 | Letter Meriwether Lewis to Thomas Jefferson, October 3, 1803 While pausing to provision his expedition, Meriwether Lewis writes to Thomas Jefferson about the scientific explorations at Big Bone Lick and his plans for the trip westward.
November 16, 1803 | Letter Thomas Jefferson to Meriwether Lewis, November 16, 1803 Thomas Jefferson updates Meriwether Lewis on political activity around the event of the Louisiana Purchase. Jefferson includes notes from the explorer Truteau that detail population and activities of some native groups living west of the Mississippi.
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.