Months before his message to congress, the president had chosen Meriwether Lewis to lead the western expedition. A fellow Virginian and son of a plantation owner near Monticello, Lewis was a captain in the army with extensive knowledge of military discipline, experience on the western frontier, and as Jefferson put it “habituated to the woods, & familiar with Indian manners & character.” Lewis had served Jefferson since early in 1801, when the president had selected him as his private secretary to aid in the president’s plan to reduce the size of the regular army. Lewis perused Jefferson’s library and discussed the western regions with him, especially after the president decided to launch the expedition. By late June 1803, Jefferson had formulated a letter of instruction that outlined an ambitious exploration agenda. In the meantime, Lewis had enlisted William Clark, experienced frontier army soldier and younger brother of Revolutionary War hero George Rogers Clark, to join him as co-captain of the Corps of Discovery.
In his letter of instructions to Meriwether Lewis, national expansion and economic development dominated Jefferson’s thinking. He was explicit:
The point of your mission is to explore the Missouri river, & such principal stream of it, as, by it’s course and communication with the waters of the Pacific ocean, whether the Columbia, Oregan, Colorado or any other river may offer the most direct & practicable water communication across this continent for the purposes of commerce.
Jefferson directed the captains to proceed up the Missouri River, note the tributaries, establish accurate maps of the region, and identify important locations for economic activity. He instructed Lewis and Clark to record information on an expansive list of scientific subjects, including flora, fauna, climate, mineral locations, and soil types that might support various kinds of agriculture. He instructed them further to note “interesting points of the portage between the heads of the Missouri, & of the water offering the best communication with the Pacific ocean [with] . . . observations . . . taken with great pains & accuracy, to be entered distinctly & intelligibly for others as well as yourself.”
Accurately plotting the landscape for posterity and future use figured prominently in the explorers’ work. Cartography and especially the accurate notations of longitude and latitude were an important part of an Enlightenment-informed scientific inventory of the region. Drawing maps of the new region had significance because they fulfilled Jefferson’s long-held desire for knowledge about the West, they established more secure claims to territory, and they were precursors of detailed surveys that would lead to land sales and settlement. In addition, the captains laid down names on their maps, names that reflected American possession of the territory, thereby extending a form of control over nature and places in the American West.
© William L. Lang, 2004
