The signs from Nogales to Tucson are a relic of a failed Carter administration pilot program that aimed to convince Americans to adopt the system of measure in use across much of the rest of the world.
The approximately 60-mile stretch of highway (or about 100 kilometers) is the only continuous highway in the U.S. with metric signs.
Some people find the signs confusing because they are not able to easily to the translation math between kilometers and miles. However, many people are opposed to changing the signs to miles. Business owners say a change to the road signs would also force them to change their advertisements. Changing from kilometers to miles would change the exit numbers they advertise.
“It had a lot of opposition because people felt it was something that relates to tourism,” Jim DiGiacomo, president of the Green Valley-Sahuarita Chamber of Commerce, said. “The hotels and businesses would have to change all of their info.”
Since Mexico uses the metric system, some people believe changing the signs to miles would hurt tourism in the area.
“Personally, I think it’s neat that my guests ask me why (the signs) are in metric,” said Jim Green, owner of The Inn at San Ignacio in Green Valley. “All of the tourists we’re talking to, there’s never been an instance where they were bothered because they weren’t in miles.”
It’s estimated that 400 signs will need to be replaced, but the state claims it does not have the funds to do so. For now, the signs will stay as they are. However, this is certainly a debate that will be revisited in the future as the current signs need to be replaced overtime due to normal wear and tear.
