The Mexican Cession is the territory that Mexico ceded to the United States in the Treaty of Guadalupe Hidalgo in 1848 after the Mexican–American War. It comprises the states of California, Texas, New Mexico, Utah, Nevada, and Arizona, and parts of Colorado, Oklahoma, Kansas, and Wyoming in the present-day Western United States. Consisting of roughly 529,000 square miles (1,370,000 km2), not including Texas, the Mexican Cession was the third-largest acquisition of territory in U.S. history, surpassed only by the 827,000-square-mile (2,140,000 km2) Louisiana Purchase of 1803 and the later 586,000-square-mile (1,520,000 km2) Alaska Purchase from Russia in 1867.