Calls to expand the six-lane road between Tucson and Phoenix to 10 lanes have prompted Arizona look at introducing commuter trains instead.
Faced with continuing traffic congestion, Arizona is waking up to rail as a practical and more affordable alternative.
In January Governor Janet Napolitano called on the Arizona transport department to look into rail-based options across the state.
Tucson Mayor Bob Walkup said: "What we need in the future is a way to move people between those populated areas and stay off the roads."
Walkup and Phoenix Mayor Phil Gordon say they've been working together on the issue for three years, and see the governor's order as a major turning-point.
This should be a good opportunity for the Arizona Rail Passenger Association
The Arizona Rail Passenger Association is a statewide membership organisation working for the expansion and improvement of rail passenger service within the state between Arizona and other states.
They want rail to be the backbone of a modern transport system for the south west of the USA.
The Arizona Rail Passenger Association is a non-profit volunteer organisation working with governments, civic leaders, corporations, and other volunteer groups.
The ARPA has been trying to re-establish an inter-city rail service to Phoenix, Tempe, and Coolidge and proposed a regional rail system using Arizona’s existing railway rights of way.
For more information: azrail.org