An old thread, but I thought I'd add on. I was leafing through a copy of the October 1974 Official Railway Guide North American Passenger Travel Edition and came across the Tucson, Cornelia & Gila Bend's listing. Monday through Friday, a ride over all 43 miles of road between Gila, AZ and Ajo, AZ in a caboose could be had for $0.97 each way. The train left Ajo at 7AM and ran north to arrive at Gila at 8:30 AM with intermediate stops allowed for at Childs, Rocky Point, Midway and Black Gap. After an hour wait at Gila, the return trip departed south at 9:25 AM and returned to Ajo at 11:00 AM. The railroad shut down in 1985, then was re-opened a decade later 1995 to assist in removing the smelting equipment at Ajo. It was closed again in 1998 and has been quiet ever since. My wife and I stopped at Gila Bend in November 2002 to find a small community and a passing train on the former SP main.
I know you asked about California and Arizona, but I will go off track (pun intended) and mention that Springfield, Missouri was the crossing point of the two major lines of the Frisco (SL-SF), so there's another choice for that location.
