The region was first settled by [[Native American]] Indians approximately 12,000 years ago. Later, in the 18th century, Spanish missionaries established a mission and a settlement that would later become Tucson. The town became a part of the United States in 1854, with the [[Gadsden Purchase]], which allowed the railroads to connect with the Midwest and California. | The region was first settled by [[Native American]] Indians approximately 12,000 years ago. Later, in the 18th century, Spanish missionaries established a mission and a settlement that would later become Tucson. The town became a part of the United States in 1854, with the [[Gadsden Purchase]], which allowed the railroads to connect with the Midwest and California. |