The outcome of the Mexican-American War in 1848 resulted in significant territorial gains for the United States. Following the war, the Treaty of Guadalupe Hidalgo was signed, which led to the U.S. acquiring lands that would become California, Arizona, New Mexico, Nevada, Utah, and parts of Colorado and Wyoming. This war, fueled by the ideology of Manifest Destiny, also intensified the debate over slavery in the newly acquired territories, setting the stage for future conflicts that would culminate in the Civil War.