This site 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.

An essay on the Treaty of Guadalupe Hidalgo written by David M. Pletcher and published by the Texas State Historical Association.

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 release all published volumes of the Correspondence of James K. Polk in searchable, open-access pdf versions. Polk's papers contain a large number of documents related to the Mexican War and the Treaty of Guadalupe Hidalgo.

The Avalon Project at Yale Law School presents the text of treaties between the United States and Mexico from 1848 to 1861.

A compilation of online resources related to the Mexican War compiled by the National Archives and Records Administration

National Archives and Records Administration.

National Archives and Records Administration presents documents and teaching activities related to the Treaty of Guadalupe Hidalgo.