This Day in the Law
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March 10

Treaty of Guadalupe Hidalgo Signed (1848)


On March 10, 1848, the Treaty of Guadalupe was signed to end the Mexican-American War. The seeds of the war had been planted three years earlier when the United States annexed Texas from Mexico and made it the 28th state of the union. Mexico had previously announced that the annexation of Texas would likely begin fighting between the nations, because Mexico considered Texas part of its lands. President James K. Polk was a known expansionist, and did very little to negotiate with Mexico. Thus, the United States and Mexico officially began war in 1846, with Mexico attempting to take California and New Mexico, and the United States occupying Mexico City.

The U.S. eventually defeated the Mexican army and captured the capital Mexico City. In September 1847, Mexico surrendered to the U.S and entered into negotiations. In 1848, Chief Clerk of the State Department, Nicholas Trist, finally managed to negotiate a treaty with Mexico. Trist, Luis G. Cuevas, Bernardo Couto, and Miguel Atristain from Mexico signed the treaty at the main altar of the old Basilica of Guadalupe at Villa Hidalgo in Mexico City on March 10, 1848.

Under the terms of the treaty, Mexico ceded Upper California and New Mexico to the United States. This area includes present-day Arizona and New Mexico and parts of Utah, Nevada, and Colorado. Mexico also relinquished all claims to Texas and recognized the Rio Grande as the southern boundary with the United States.

The United States agreed to pay Mexico $15 million for the land it was given, and to pay its own American citizens the debts owed to them by the Mexican government. Other provisions included protection of property and civil rights of Mexican nationals living within the new boundaries of the United States, the promise of the United States to police its boundaries, and a guarantee that Mexicans who remained more than one year in the ceded lands would automatically become full-fledged American citizens.