Possible Clues:

• City east of San Diego
• Southwestern Arizona city
• Arizona county known as the Winter Salad Bowl Capital
• Desert straddling the US-Mexico border
• City near the confluence of the Colorado and Gila rivers
• Where the 3:10 train was heading to in Hollywood western films of the same name from 1957 and 2007
• City in the Sonoran Desert
• Arizona's 'Sunniest City on Earth'
• Arizona town to which Christian Bale and Russell Crowe took the 3:10 in 2007?
• Arizona Western College city