What was the name of the land purchased from mexico by the united
states that included the southern area of new mexico and arizona to
build a railroad?

venta de la mesilla

Explanation:

Venta de La Mesilla (Sale of La Mesilla),[2] is a 29,670-square-mile (76,800 km2) region of present-day southern Arizona and southwestern New Mexico that the United States acquired from Mexico by the Treaty of Mesilla, which took effect on June 8, 1854. The purchase included lands south of the Gila River and west of the Rio Grande where the U.S. wanted to build a transcontinental railroad along a deep southern route, which the Southern Pacific Railroad later completed in 1881–1883. The purchase also aimed to resolve other border issues.