La Gran LíneaThe Treaty of Guadalupe Hildalgo, which officially ended the U. S. Mexican War in 1848, cost Mexico half its territory, while the United States gained land that became California, Nevada, Utah, Texas, and parts of Colorado, Arizona, and New Mexico. Because the new United States Mexico border ran through territory that was still incompletely mapped, the treaty also called for government commissions from both nations to locate and mark the boundary on