Mexico Cedes Half Its Territory in the Treaty of Guadalupe Hidalgo

On 2 February 1848, representatives of the United States and Mexico met in the village of Guadalupe Hidalgo, just north of Mexico City, to sign the Treaty of Guadalupe Hidalgo. United States forces under General Winfield Scott had occupied Mexico City since September 1847, leaving the defeated Mexican government fractured and facing widespread domestic unrest. The American diplomat Nicholas Trist concluded the accord alongside Mexican plenipotentiaries Jose Bernardo Couto, Miguel de Atristain, and Luis Gonzaga Cuevas, despite President James K. Polk having formally recalled Trist after earlier peace talks had stalled.

The agreement resolved the Mexican-American War by formally adjusting the international border. Mexico relinquished all claims to Texas, accepted the Rio Grande as the boundary, and surrendered roughly 55 percent of its pre-war territorial claims. In the United States, the newly acquired territory outside of Texas became known as the Mexican Cession, encompassing Alta California and western Santa Fe de Nuevo Mexico. In exchange, the United States agreed to pay Mexico 15 million dollars, 3 million on ratification and the rest in annual installments with interest, and assumed 3.25 million dollars in existing claims owed by Mexico to United States citizens.