This website is a joint project of the Center for Greater Southwestern Studies and the Library at the University of Texas at Arlington. It contains essays, biographies, and a timeline that provide background information about the war, as well as primary sources from the war such as proclamations, letters, diaries, images, maps, music, and poetry.

This site contains an essay on the Mexican War, as well as a chronology of events and a bibliography. It also includes images, government documents, maps, statistics, and a list of historical sites associated with the war.

The James K. Polk Project and the University of Tennessee Press have arranged with Newfound Press, the digital imprint of the University of Tennessee Libraries, to make all volumes of the Correspondence of James K. Polk available online at no charge. Polk's papers contain a large number of documents related to the Mexican War.

The Northern Illinois University Digital Library contains a historical overview of the Mexican-American War (1846-1848), as well as primary source materials related to the conflict.

A compilation of resources on the Mexican War compiled by the Archives Library Information Center at the National Archives and Records Administration. It includes links to documents and images at the National Archives, as well as links to external sites.

The U.S. Army Center of Military History provides the full text of online books related to Mexican War and a bibliography of selected readings.

The National Park Service provides background information on the battle at Palo Alto and the Mexican War in general.