The Gadsden Purchase, also called the Treaty of Mesilla (in Spanish, Venta de La Mesilla), was the acquisition by the United States of a region of southern Arizona and southwestern New Mexico from Mexico. The first draft was signed on December 31, 1853, and it took effect on June 8, 1854. Before it, the Mesilla Valley sat on the border; afterwards Mesilla was the largest town in the area.
Glossary · History
Gadsden Purchase
The 1853 treaty (also the Treaty of Mesilla) that bought the land around Las Cruces from Mexico.