Kilometers to miles: debate over changing highway signs

Highway sign displaying distance in kilometers near I-19 and Ajo in Tucson, Ariz. Photo by Brian Valencia
Highway sign displaying distance in kilometers near I-19 and Ajo in Tucson, Ariz. Photo by Brian Valencia

Driving along I-19, you might have to remember your grade school days of learning the metric system.

The highway signs along I-19 show distances in kilometers not miles. Many people don’t give it much thought but a change to miles could affect businesses and the relationship with America’s third biggest trading partner.

The signs were a failed attempt by President Carter to convince Americans to adopt the worldwide system. The 60-mile (or 100 kilometer) stretch from Nogales to Tucson is the only continuous highway in the U.S. using the metric system.

Interstate 19’s completion in the late 1970s made it the perfect candidate for the new experiment.

“I think they should have it in miles because it can be confusing at times,” said Alex Gill of Tucson. “Mexico doesn’t have signs in miles for Americans.”

For others, it is seen as a kind gesture to the Mexican citizens who do business on this side of the border. All destination signs are also in the metric system, which help with trucks coming from Mexico.

Residents and businesses along the highway don’t necessarily rely on the metric system.

“We don’t try to say seven kilometers or whatever it is,” said Kurt Ahrens, a business owner from Rio Rico. “They just converted to miles and talk miles.”

Ahrens ignores distance all together by using the exit numbers to give people directions.

Eventually the signs will be changed due to natural wear and tear but it’s not known if they will continue using kilometers or convert to miles. Dustin Krugel, a spokesman for ADOT, said the most difficult part is finding the money for the project.

“When funding has been identified that’s when we will move to the next step and look to get the communities input on this,” Krugel said. “We know that some of the business owners are concerned that some of their promotional materials may have to be changed.”

It is not clear if the nearly 400 signs will be converted to miles when the signs are replaced. One option is to have them in both, miles and kilometers. Either way the project would consist of replacing the signs to brighter and easier to read signs.

Krugel said when planning, the project ADOT will seek input from cities, businesses and the Hispanic community.

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