February 2
Treaty of Guadalupe Hidalgo Ends Mexican-American War
The treaty that concluded the Mexican-American War transferred more than half a million square miles of territory to the United States and established the Rio Grande as the southern boundary of Texas.
Summary
The Mexican-American War, sparked by disputes over Texas and border territories, had seen U.S. forces advance deep into Mexico by 1847 under generals like Winfield Scott and Zachary Taylor. With Mexico facing military collapse and internal instability, negotiators met in the village of Guadalupe Hidalgo near Mexico City. On February 2, 1848, the Treaty of Guadalupe Hidalgo was signed, with Mexico ceding vast lands including present-day California, Nevada, Utah, New Mexico, Arizona, and parts of Colorado and Wyoming in exchange for $15 million and assumption of certain claims. The agreement also established the Rio Grande as the Texas boundary. Ratification followed quickly in the U.S. Senate, formally concluding the conflict.
Context
The Mexican-American War grew out of longstanding disputes over Texas and the border between Mexico and the expanding United States. Mexico had never recognized the independence of the Republic of Texas after its revolt in 1836, and the American annexation of Texas in 1845 heightened tensions over whether the border lay at the Nueces River or the Rio Grande farther south. President James K. Polk, committed to territorial expansion, ordered troops into the disputed region in early 1846, and clashes soon escalated into full-scale war.
What Happened
By the fall of 1847, U.S. forces under General Winfield Scott had captured Mexico City, leaving the Mexican government in disarray and eager for an end to hostilities. Polk dispatched Nicholas Trist, a State Department official, as his representative to negotiate peace terms. Despite a recall order from Washington, Trist remained and met with a Mexican commission consisting of José Bernardo Couto, Miguel de Atristain, and Luis Gonzaga Cuevas in the village of Guadalupe Hidalgo just outside the capital.
Aftermath
The two sides signed the treaty on February 2, 1848. The U.S. Senate approved it on March 10 by a vote of 38 to 16, and Mexico completed its ratification process on May 19. Ratifications were exchanged on May 30, formally ending the war. Mexico received $15 million from the United States and relief from certain private claims, while the United States gained clear title to vast new lands.
Legacy
The Mexican Cession dramatically enlarged the United States, incorporating regions that would become all or part of nine states and advancing the vision of Manifest Destiny. The addition of new territory reignited fierce debates over the extension of slavery, contributing to the sectional crisis that led to the Civil War. The treaty also fixed the basic outline of the modern U.S.-Mexico border, though later adjustments such as the Gadsden Purchase refined its southern reaches.
Why It Matters
The treaty dramatically expanded U.S. territory by over 500,000 square miles, fulfilling much of the concept of Manifest Destiny and integrating new regions with diverse populations and resources into the nation. It intensified debates over slavery in the acquired lands, fueling sectional tensions that contributed to the Civil War. Long-term, it established the modern U.S.-Mexico border framework still in place today and shaped bilateral relations for generations.
Related Questions
What territory did Mexico cede under the treaty?
Mexico ceded approximately 525,000 square miles, including present-day California, Nevada, Utah, most of Arizona, and parts of New Mexico, Colorado, and Wyoming.
How much did the United States pay Mexico?
The United States paid Mexico $15 million and assumed roughly $3.25 million in debts owed by Mexico to American citizens.
Why was Nicholas Trist recalled yet still negotiated the treaty?
President Polk grew dissatisfied with Trist's progress and ordered his return, but Trist stayed in Mexico and completed the negotiations anyway, producing terms the administration ultimately accepted.
What role did the treaty play in debates over slavery?
The vast new territories intensified the question of whether slavery would be permitted in the West, deepening sectional divisions that contributed to the Civil War.
How did the treaty affect the U.S.-Mexico border?
It established the Rio Grande as the boundary for Texas and set the basic framework for the modern international border, later adjusted by the Gadsden Purchase.
Related Portfolio Site
America 250 Atlas: Treaty of Guadalupe Hidalgo Ends Mexican-American War is part of U.S. presidential, constitutional, or national civic history.
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Sources
- Treaty of Guadalupe Hidalgo is signed, HISTORY. Accessed 2026-07-08.
- Treaty of Guadalupe Hidalgo, Wikimedia Foundation. Accessed 2026-07-08.