Like so many other exploration stories, the Lewis and Clark journey was shaped by the search for navigable rivers, inspired by the quest for Edens, and driven by competition for empire. Thomas Jefferson was motivated by these aspirations when he drafted instructions for his explorers, sending them up the Missouri River in search of a passage to the Pacific. Writing to William Dunbar just a month after Lewis and Clark left Fort Mandan, Jefferson emphasized the importance of rivers in his plan for western exploration and national expansion. "We shall delineate with correctness the great arteries of this great country. " River highways could take Americans into an Eden, Jefferson's vision of the West as the "Garden of the World. " And those same rivers might be nature's out-lines and borders for empire. "Future generations would, " so the president told his friend, "fill up the canvas we begin. "
Source: Library of Congress, Exhibits, "Rivers, Edens, Empires: Lewis & Clark and the Revealing of America. "
Manifest Destiny is a belief that the United States had a mandate to expand its civilization westward. Jefferson's vision of an empire with future generations filling up "the canvas we begin" most closely resembles the idea of Manifest Destiny