[4] The Fort Huachuca installation is located in Cochise County, approximately 15 miles (24 km) north of the Mexican border, and is within the city of Sierra Vista.

It covered the northeast quadrant of the state, from Flagstaff to the New Mexico border.

Most of its population, however, was located in the northeastern portion of the Valley of the Sun, including Tempe and Scottsdale.

It included parts of Mesa, Chandler and all of Gilbert as well as the fast-growing town of Queen Creek.

The district and its predecessors had seen its share of Phoenix gradually reduced amid the Valley's explosive growth in the second half of the 20th century.