SOURCE: An introduction to The Journals of Lewis and Clark, edited by Bernard DeVoto, Houghton Mifflin Company, 1953, pp. xv-lii.

In the following essay, DeVoto offers a comprehensive survey of the political and historical state of affairs both before and during the expedition, and provides a detailed overview of the expedition itself—noting its objectives, its major finds and contributions, as well as its principal players.

Toward the end of November 1802, President Thomas Jefferson asked the Spanish minister a carefully unofficial question. Would the Spanish court “take it badly,” he inquired, if the United States should send a small expedition to “explore the course of the Missouri River,” which lay wholly in the still Spanish territory of Louisiana? The ostensible reason for such an expedition, he went on, would be the advancement of commerce, since Congress had no power to appropriate money for its real object. But “in reality...