The Gadsden Purchase is a 30,000 mi2 (77,700 km2) region of what is today southern Arizona and New Mexico that was purchased by the United States from Mexico in 1853. The purpose of the purchase was to allow for the construction of a southern route for a transcontinental railroad, which was never built. Another rationale for the purchase is to give Mexico more money in compensation for the small amount paid for the lands taken by the United States after the Mexican-American War. James Gadsden (U.S. Minister to Mexico) and Antonio Lopez de Santa Anna (President of Mexico) agreed on the price of $10,000,000 USD on December 30, 1853.
The original plans of the purchase called for a much larger portion of land to be acquired from Mexico extending far enough South to encompass Baja California. These original boundaries were not only opposed by the Mexican people, but also by anti-Slavery senators who saw this as a move towards more slave territory. Even the small final strip of land that was finally acquired was enough to anger the Mexican people who watched as Antonio Lopez de Santa Anna squandered the money. This would be one of the major contributing factors that lead to the end of Santa Anna's political career.
On the Sonoita River in present-day southern Arizona, the United States Army established Fort Buchanan on November 17, 1856 in order to help control new land.
