The Treaty of Guadalupe Hidalgo (Spanish: Tratado de Guadalupe Hidalgo), officially titled the Treaty of Peace, Friendship, Limits and Settlement between the United States of America and the Mexican Republic, is the peace treaty that was signed on 2 February 1848, in the Villa de Guadalupe Hidalgo (now a neighborhood of Mexico City) between the United States and Mexico that ended the Mexican–American War (1846–1848). The treaty was ratified by the United States on 10 March and by Mexico on 19 May. The ratifications were exchanged on 30 May, and the treaty was proclaimed on 4 July 1848.With the defeat of its army and the fall of its capital in September 1847, Mexico entered into negotiations with the U.S. peace envoy, Nicholas Trist, to end the war. On the Mexican side, there were factions that did not concede defeat or seek to engage in negotiations. The treaty called for the United States to pay US$15 million to Mexico and to pay off the claims of American citizens against Mexico up to US$5 million. It gave the United States the Rio Grande as a boundary for Texas, and gave the U.S. ownership of California, Nevada, Utah and Colorado, as well as an area comprising most of New Mexico, and approximately two thirds of Arizona. Mexicans in those annexed areas had the choice of relocating to within Mexico's new boundaries or receiving American citizenship with full civil rights.

The U.S. Senate advised and consented to ratification of the treaty by a vote of 38–14. The opponents of this treaty were led by the Whigs, who had opposed the war and rejected manifest destiny in general, and rejected this expansion in particular. The amount of land gained by the United States from Mexico was further increased as a result of the Gadsden Purchase of 1853, which ceded parts of present-day southern Arizona and New Mexico to the United States.