The Treaty of Guadalupe Hidalgo was signed on February 2, 1848, officially ending the Mexican-American War. This treaty resulted in Mexico ceding a vast portion of its northern territories to the United States, including present-day California, Arizona, New Mexico, Nevada, Utah, and parts of Colorado and Wyoming. In return, the U.S. agreed to pay Mexico $15 million and settle claims of American citizens against Mexico. This acquisition significantly expanded U.S. territory and contributed to the contentious debates over slavery in the new states formed from these lands, setting the stage for future conflicts.