PBS
Pbs: The West: The Louisiana Purchase Treaty
This site from PBS contains a transcription of the three documents concerning the purchase of Louisiana from France. There is a link to other documents.
PBS
Pbs: New Perspectives on the West
This in-depth resource presents a history of the American West from pre-Columbian times until World War I with profiles, documents, and images. It encourages visitors to link these into patterns of historical meaning for themselves....
Yale University
Avalon Project: The Louisiana Purchase 1803
A series of primary source documents all related to the Louisiana Purchase. Includes the text of the final agreement, speeches by Jefferson and others. Great stuff!
US National Archives
Nara: American Originals
A collection of important documents highlighting events in United States history. These at one point were on display in the Rotunda of the National Archives Building. Each document is accompanied by a short description of its significance.
US National Archives
Nara: American Originals: Louisiana Purchase Treaty
Wonderful NARA site that provides pictures of the original treaty and agreements of the Louisiana Purchase. Brief introduction discusses the amount of land purchased and the cost per acre described by the Purchase.
Library of Congress
Loc: Teachers: Journeys West
A series of lessons utilizing primary texts, including narratives, photographs, and maps, through which students explore the following question: "What motivated thousands of people to journey west during the 1800s?"
PBS
Pbs: Louisiana Purchase: April 30, 1803
This PBS site provides images of all pages of the original Louisiana Purchase, with a transcript.