From 1848 to 1854, the Gila River north of this site marked the international border of the United States and Mexico. James Gadsden negotiated the purchase of thirty-eight thousand square miles of “Wild country” for fifteen million dollars in gold, but the agreement was amended to ten million dollars for twenty-nine thousand six hundred forty square miles. The Gadsden Purchase maintained southern railroad and wagon routes while preserving Mexico's link to Baja, California. Today it comprises twenty-four percent of Arizona's total land area.