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 20, 1803 | Letter Thomas Jefferson to Albert Gallatin, March 20, 1803 As Jefferson and Albert Gallatin plan Lewis and Clark's expedition, questions over geography and cartography continue as Jefferson reveals his familiarity with maps of the West.
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.
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.