The Treaty of Guadalupe Hidalgo En Español The Treaty of Guadalupe Hidalgo, that brought an official end to the Mexican-American War (1846-1848), was signed on February 2, 1848, at Guadalupe Hidalgo, a city north of the capital where the Mexican government had fled with the advance of U.S. forces. By its terms, Mexico ceded 55 percent of its territory, including the present-day states California, Nevada, Utah, New Mexico, most of Arizona and Colorado, and parts of Oklahoma, Kansas, and Wyoming.