The Gadsden Purchase (known in Mexico as Spanish: Venta de La Mesilla, "Sale of La Mesilla '') is a 29,670 - square - mile (76,800 km) region of present - day southern Arizona and southwestern New Mexico that the United States purchased via a treaty signed on December 30, 1853, by James Gadsden, U.S. ambassador to Mexico at that time. The U.S. Senate voted in favor of ratifying it with amendments on April 25, 1854, and then transmitted it to 14th President Franklin Pierce. Mexico 's government and its General Congress or Congress of the Union took final approval action on June 8, 1854. The purchase was the last substantial territorial acquisition in the contiguous United States. The U.S. sought the land as a better route for the construction of the southern transcontinental railway line, and the financially - strapped government of Antonio López de Santa Anna agreed to the sale, which netted Mexico $10 million (equivalent to $270 million in 2017). After the devastating loss of Mexican territory to the U.S. in the Mexican -- American War (1846 -- 48) and the continued filibustering by U.S. citizens, Santa Anna may have calculated it was better to yield territory by treaty and receive payment rather than have the territory simply seized by the U.S.
what was the main goal of the gadsden purchase in 1853
a better route for the construction of the southern transcontinental railway line