Gadsden Purchase

a tract of 45,535 sq. mi. (117,935 sq. km), now contained in New Mexico and Arizona, purchased for $10,000,000 from Mexico in 1853, the treaty being negotiated by James Gadsden.

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(Dec. 30, 1853) U.S. purchase of land in Mexico.

Following the conquest of much of northern Mexico in the Mexican War (1848), advocates of a southern transcontinental railroad endorsed the purchase of 30,000 sq mi (78,000 sq km) of northern Mexican territory, now southern Arizona and southern New Mexico. The purchase was negotiated by James Gadsden, U.S. minister to Mexico, for $10 million. The acquisition fixed the borders of the later 48 contiguous states.

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▪ United States-Mexican history

also called  Treaty of La Mesilla 

      (Dec. 30, 1853), transaction that followed the conquest of much of northern Mexico by the United States in 1848. Known in Mexican history as the sale of the Mesilla Valley, it assigned to the United States nearly 30,000 additional square miles (78,000 square km) of northern Mexican territory (La Mesilla), now southern Arizona and southern New Mexico, in exchange for $10,000,000. Prompted in part by advocates of a southern transcontinental railroad, for which the most practical route would pass through the acquired territory, the purchase was negotiated by the U.S. minister to Mexico, James Gadsden (Gadsden, James). Residents of the territory were to enjoy the same protections as those afforded to residents of the area ceded to the United States earlier by the Treaty of Guadalupe Hidalgo (1848).

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