When a young United States finalized the Louisiana Purchase in 1803, they in some ways literally didn't know what they were getting. Certainly a number of surveyors, explorers, and Native Americans had traversed different segments of this vast territory, but it had by no means been completely explored and documented. Recently, the American Memory Project at the Library of Congress created this rather delightful online collection that tells the historical and cultural story of the European explorations of these lands. The collection contains 119 items such as a Native American map of the Upper Missouri from 1801 and the "Accurate Map of North America" by Emmanuel Bowen from 1767. First-time visitors should make a point of reading the 118-page explanatory essay offered here. It covers such topics as the cartographic setting of the Purchase and Louisiana's tenure as a Spanish colony.