As part of his instructions to Lewis, President Jefferson made it clear that his “observations [were] to be taken with great pains and accuracy, to be entered distinctly and intelligibly for others as well as yourself, . . . “. In order to fulfill this instructional mandate, the making of maps became a vital part of the expedition’s activities. Join experts on the original expedition as well as experts from the National Geospatial-Intelligence Agency to compare the “then and now” of cartography. From the Series:Lewis and Clark Then and Now