Although U.S. troops occupied their capital, Mexican leaders hesitated to cede territory. This caused negotiations to drag on for months. Finally, on February 2, 1848, the U.S and Mexico came to terms. In the Treaty of Guadalupe-Hidalgo, Mexico agreed to surrender all claims to Texas and accept the Rio Grande as the boundary of that state.
Mexico also agreed to sell its New Mexico and Upper California territories to the U.S. for the price of $15 million. The treaty resulted in Mexico losing half its national territory and the U.S. doubling in size.
This territorial exchange had long-term effects on both nations. The war and treaty extended the U.S. to the Pacific Ocean and provided a bounty of ports, minerals, and natural resources for a growing country. The abundance of lands also produced debates about extending slavery into the West. That dispute would help spark a nation-defining civil war.
In Mexico, the loss of battles and territories was a national trauma. Political and military leaders challenged each other on the best way to revive their troubled country. Mexico descended into a long period of turmoil, civil war, and foreign intervention.
But the war also inspired new leaders who were determined to avoid additional humiliation for their country. The new generation eventually united Mexico, forced out foreign invaders, and established the foundations of a modern state.
Perhaps the most enduring effect of the war, however, is on U.S.-Mexican relations. While the war is remembered with passion south of the border, it is often overlooked to the north. And, although the two countries have developed strong bonds and friendly ties since 1848, these neighbors continue to struggle with distrust and misunderstandings created by the war, its effects, and its legacy.