Treaty of Guadalupe Hidalgo

The Treaty of Guadalupe Hidalgo, signed on February 2, 1848, ended the Mexican War, recognized the annexation of Texas to the United States (consummated nearly three years before), ceded to the United States Upper California (the modern state of California) and nearly all of the present American Southwest between California and Texas, and attempted to protect the interests of the existing population in the cession. The treaty traced the boundary between the United States and Mexico from the Gulf of Mexico up the main channel of the Rio Grande to the southern boundary of the Mexican province of New Mexico. The line followed the southern boundary of New Mexico to its western boundary and north to the first branch of the Gila River, then down the Gila to its intersection with the Colorado River, and finally along the old Spanish-Mexican division line between Upper and Lower California. The exact boundary was to be surveyed and marked by a joint commission to be appointed by the two governments within a year.

The negotiation of the treaty presented many knotty problems, mostly caused by the Mexicans' sense of honor and their acceptance of defeat. After Gen. Winfield Scott had captured Veracruz and pushed into the interior of Mexico, President James K. Polk and Secretary of State James Buchanan sent Nicholas P. Trist, from the Department of State, to join him in the hope that with plenipotentiary powers and full instructions the two could take advantage of any crack in Mexican resolve to push through negotiations. Scott and Trist managed to establish communications with the Mexican government by way of British legation officials in Mexico City, who were anxious to see peace return before Mexico was entirely crushed. Antonio López de Santa Anna, having returned from exile in Havana as part of the Polk administration’s attempt to undermine Mexico’s ability to withstand a U.S. invasion, decided to lead Mexico’s defenses, but was ultimately unable to create enough coordinated resistance to block Scott from occupying Mexico City. Thereupon Santa Anna resigned, and the rest of the Mexican government fled to a provisional capital about a hundred miles to the north. At this point an indefinite deadlock might have resulted, for the weak Mexican administration succeeding Santa Anna dared not act, and the Mexican congress, which split into a number of peace and war factions, did everything possible to avoid responsibility. By the end of November, after weeks of jockeying, Trist, aided by British diplomats, managed to persuade the Mexicans to send a peace commission to Mexico City and at least exchange proposals. At that point a dispatch arrived from the impatient Polk instructing Trist to give up the effort and return home. Pressed by Scott and the other American generals and by the British, Trist decided to disobey his orders and stay.

The active negotiations, which lasted about a month, were delayed at every point by haggling over details and slow correspondence between the Mexican commissioners and their government, a hundred miles away, which resisted U.S. demands. At first the Mexicans, based long-established internal borders, would recognize Texas territory only to the Nueces River. They also resisted the cession of New Mexico, and a particularly bitter argument arose over the cession of San Diego, which they denied had ever been a part of Upper California. Mexico’s bargaining position, weakened after Scott’s capture of Mexico City, led to both territorial concessions and a lowering of the American purchase price of $15 million, half of the original Mexican offer. When Polk received the completed treaty he was affronted by Trist's disobedience and stopped his salary. On further consideration, he decided to submit the treaty to the Senate because it met his minimum instructions concerning the boundary and because any continuation of the war risked serious disunion in the country during an election year. The nation received the treaty with relief, although there was debate over the expansion of slave territory and the extent of U.S. responsibility, the Senate approved it after a few minor changes, with a few votes to spare over the required two-thirds majority. The execution of the treaty was generally satisfactory to both sides, except for its requirement that the United States prevent Indian raids into Mexico, an almost impossible task on a long, unsettled frontier. Also to prove problematic were the provisions that offered citizenship to the existing Mexican population and that guaranteed property rights within the ceded territory. For the Tejano population living in the area controlled by the former Republic of Texas, these provisions were unimportant as their citizenship had previously been established, but for the Mexican population along Rio Grande and those of New Mexico and California, land disputes and questions of citizenship would profoundly affect their rights for over a century to come. See also BOUNDARIES.

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Will Fowler, Santa Anna of Mexico (Lincoln: University of Nebraska Press, 2007). Richard Griswold del Castillo, The Treaty of Guadalupe Hidalgo: A Legacy of Conflict (Norman: University of Oklahoma Press, 1992). Hunter Miller, ed., Treaties and Other International Acts of the United States of America (8 vols., Washington: GPO, 1931–48). David M. Pletcher, The Diplomacy of Annexation: Texas, Oregon, and the Mexican War (Columbia: University of Missouri Press, 1973). George Lockhart Rives, The United States and Mexico, 1821–1848 (2 vols., New York: Scribner, 1913). Richard Bruce Winders, Crisis in the Southwest: The United States, Mexico, and the Struggle over Texas (Wilmington, DE: Scholarly Resources, 2002).

The following, adapted from the Chicago Manual of Style, 15th edition, is the preferred citation for this entry.

David Pletcher Revised by Jesús "Frank" de la Teja, “Treaty of Guadalupe Hidalgo,” Handbook of Texas Online, accessed September 11, 2024, https://www.tshaonline.org/handbook/entries/treaty-of-guadalupe-hidalgo.

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