"Gadsden Purchase" is the name given to the strip of land, now the southern part of New Mexico and Arizona, purchased by the U.S. government from Mexico in 1853. Even with the ill will of the Mexican War, which ended in 1848, the Mexican government was willing to arrange for more of its land to be controlled by the United States--but for a price. James Gadsden, an American diplomat, signed a treaty December 30,1853, which provided for Mexico to sell to the United States a rectangular strip of land of about 26,640 square miles in the Mesilla Valley south of the Gila River. Purchase price was $10 million. The land was important as a route for a railroad through the Southwest to the Pacific.