What is the name of the us acquisition of the southern strip of the land in Arizona and New Mexico in 1853

Gasden Purchase--the strip of land purchased from Mexico in 1853 was negotiated by James Gasden.

The US wanted this strip of land to complete the southern branch of the Transcontinental Railroad. Gasden was the minister to Mexico and sent to negotiate the purchase of the land as well as create a final border agreement with Mexican president, Santa Anna. The land was purchased for $10 million and settled the US-Mexico border.