The Mexican Cession of 1848 refers to the lands ceded or surrendered to the United States by Mexico at the end of the Mexican–American War.[1] The territory became the states of California, Nevada, Utah and Arizona.[1] It was agreed to in the Treaty of Guadalupe Hidalgo, which formally ended the war (1847–1848) between Mexico and the United States.[2] The treaty was signed on 2 February 1848.[2] The Cession added 500,000 square miles (1,300,000 km2) of territory to the southwestern United States. It also contributed to the United States emerging as a world power in the late the 19th century.[2]