<P> The Mexican Cession is the region in the modern - day southwestern United States that Mexico ceded to the U.S. in the Treaty of Guadalupe Hidalgo in 1848 . This region had not been part of the areas east of the Rio Grande which had been claimed by the Republic of Texas , though the Texas annexation resolution two years earlier had not specified the southern and western boundary of the new State of Texas . The Mexican Cession ( 529,000 sq. miles ) was the third largest acquisition of territory in US history . The largest was the Louisiana Purchase , with some 827,000 sq. miles , followed by the acquisition of Alaska ( about 586,000 sq. miles ) . </P>
<P> The Mexican Cession is the region in the modern - day southwestern United States that Mexico ceded to the U.S. in the Treaty of Guadalupe Hidalgo in 1848 . This region had not been part of the areas east of the Rio Grande which had been claimed by the Republic of Texas , though the Texas annexation resolution two years earlier had not specified the southern and western boundary of the new State of Texas . The Mexican Cession ( 529,000 sq. miles ) was the third largest acquisition of territory in US history . The largest was the Louisiana Purchase , with some 827,000 sq. miles , followed by the acquisition of Alaska ( about 586,000 sq. miles ) . </P>
when did the us buy land from mexico
when did the us buy land from mexico
1848
1848