The United States acquired almost all the area of New Mexico from Mexico in 1848. The United States acquired a small area, comprising the southwestern corner of New Mexico, from Mexico in 1853 as part of the Gadsden Purchase. New Mexico Territory was organized from the acquired area December 13, 1850, and included most of present-day Arizona and New Mexico as well as parts of Colorado and Nevada. The territory was reduced with the organization of Colorado Territory in 1861 and Arizona Territory in 1863 to assume generally the same boundary as the present state. New Mexico was admitted to the Union on January 6, 1912, as the 47th state.