Final answer:
The main reason for the Gadsden Purchase in 1853 was to enable a southern route for the transcontinental railroad. This was part of the broader US mission of westward expansion, known as Manifest Destiny.
Step-by-step explanation:
The United States negotiated the Gadsden Purchase in 1853 primarily to support the idea of a southern route for the transcontinental railroad. The territory acquired through this transaction, located in the present-day states of Arizona and New Mexico, offered a viable path for a southern railway that would link the eastern and western parts of the country. This expansion was part of America's broader Manifest Destiny ideology, which asserted that the US had a divine mandate to spread across the continent. American expansionists, particularly those in the South, supported this idea fervently.
While mining rights and issues with Native Americans were concerns in the Southwest, they were not the primary reasons for the Gadsden Purchase. Similarly, it was not aimed at establishing James Gadsden as a territorial governor.
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