The Louisiana Purchase -The National Archives has the text of the three agreements completing the purchase of the Louisiana Territory in 1803, as well as images of the actual treaty. Look for Napoleon's signature!

Annexation—Celebrating 150 Years of Texas Statehood - The Texas Humanities Center organized this on-line exhibit based on actual artifacts and exhibits at the Capitol Center in Austin. The site contains various images from the annexation period and can be navigated either through a text outline or through a gallery of images. A few learning activities are also available, including one relating to images of the Alamo.

The U.S.-Mexican War - PBS created this site as a companion to their documentary on the war between the United States and Mexico. Dialogues are presented from different perspectives and include a great deal of information on Manifest Destiny. Students can also respond to the dialogues in an on-line discussion area.

The Avalon Project at the Yale Law School provides a variety of primary resource documents relating to Manifest Destiny, including the purchase of Florida, the agreement on the Oregon Country, and the Gadsden Purchase Treaty.