Gadsden Purchase

The Gadsden Purchase was a area of land sold by Mexico to the United States in 1854. It is now part of Arizona and New Mexico, south of the Gila River and west of the Rio Grande. Its size was . The United States paid Mexico 10,000,000 dollars, which is worth 230,000,000 dollars in 2019 money. This trade was officially called the Treaty of Mesilla.
Background.
The Mexican-American War had ended in 1848. The United States won the war. Both countries agreed to the Treaty of Guadalupe Hidalgo, which gave the United States a very big part of Mexico: the Mexican Cession, an area of more than . In return, the United States paid Mexico 15,000,000 dollars.
After 1848, Mexico and the United States did not agree where the border was. Both countries claimed the Mesilla Valley as part of their own country. Businessmen from the southern states wanted to build a new transcontinental railroad that would cross the southern part of the country. They wanted the railroad to go through the Mesilla Valley. Jefferson Davis, who at that time was the US Secretary of War, supported that idea. James Gadsden was sent to buy the land from Mexico. He wanted to buy much more land, including Tamaulipas, Coahuila, Nuevo Leon, and parts of Chihuahua and Sonora, but the Mexican president, Antonio Lopez de Santa Anna, did not want to sell it to him.
Establishment of purchase.
A treaty was signed on December 30, 1853. This treaty would have given to the United States and 15,000,000 dollars to Mexico. Many US Senators did not agree with this: they wanted to buy less land. On April 25, 1854, the US Senate accepted the new, smaller purchase. President Franklin Pierce signed the treaty, and then sent it to President Santa Anna, who signed it on June 8, 1854. Many Mexicans were angry with Santa Anna after he signed the treaty.