The treaty that ended the war between the United States and Mexico is known as the Treaty of Guadalupe Hidalgo, signed on February 2, 1848. This treaty concluded the Mexican-American War, which began in 1846, primarily driven by territorial disputes following the annexation of Texas by the U.S. Under the terms of the treaty, Mexico ceded a significant portion of its northern territories, including present-day California, Nevada, Utah, Arizona, and parts of Colorado and New Mexico, to the United States. The treaty significantly altered the border and increased U.S. territory, further intensifying debates over slavery and its expansion.