How did the US get territory of Arizona?

The United States acquired the Arizona territory through the Gadsden Purchase, which was a treaty signed between the United States and Mexico in 1853. The treaty established the current boundary between the United States and Mexico, and ceded territory from Mexico to the United States that included present-day Arizona and New Mexico, as well as parts of present-day Colorado, Nevada, and Utah. In exchange for this land, the United States paid Mexico $10 million.