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How did the Treaty of Guadalupe Hidalgo establish the U.S.-Mexico border?

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How the Mexican-American War changed the U.S. forever — Mexican-American War Learn how the Mexican-American War ultimately pushed the United States closer to civil war.

The Treaty of Guadalupe Hidalgo, signed on February 2, 1848, formally ended the Mexican-American War and established the boundary between the United States and Mexico along the Rio Grande and the Gila River.1

Prior to this treaty, the border had been a subject of intense dispute, with Mexico maintaining that the boundary was at the Nueces River, while the United States claimed it was at the Rio Grande. Through the treaty, Mexico relinquished more than 525,000 square miles of territory to the United States, an acquisition known as the Mexican Cession. In exchange, the United States paid $15,000,000 and agreed to settle over $3,000,000 in claims made by U.S. citizens against Mexico. This border was later finalized by the Gadsden Purchase in 1853, which added further territory in present-day southern Arizona and New Mexico.231