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Ren Gudino

Arizona Highways Hold onto History (and the Metric System)

Did you know that our national interstate system is 46, 876 miles long? Oh wait, it's actually 46, 812.6 miles long and 102 kilometers. That’s right! We have one interstate that is marked by kilometers the entire way through and that’s Arizona’s Interstate-19. From Nogales to the Mexican border, this south-eastern interstate has held onto kilometers as a historical marker, since its completion in 1978, and is only one of Arizona’s highways holding onto history.



Why were we using kilometers in 1978? In 1975, Congress passed the Metric Conversion Act, declaring the metric system the preferred system of measurement. This act was more of a suggestion and a campaign was started to educate our school children on the metric system. Interstate 19 was a part of a pilot program to convert all of the mile markers to kilometers, and crews started working on converting all of its signs to be ready for its completion three years later.



This campaign lasted for about seven years until it was dismantled by Ronald Reagan in 1982. In those seven years, only one other interstate followed the same example: Interstate 265 in Louisville, Kentucky—but it’s a much smaller stretch marked by kilometers. In this time, the United States hadn’t made a serious effort to convert, leaving very little that needed to be changed back with the end of the campaign. Or rather, not changed back, since Arizona refused to change their kilometric markers and fought to keep them.


Even though President Carter managed to start the U.S. Metric Board, when an anti-metric outpour started, Americans pushed against it. (This will be talked about more in depth next week.) In an act of pro-metric rebellion, Arizona refused to change their metric signage back to imperial measurements. Instead, the imperial mile markers are placed alongside the interstate at a right angle to the road—not facing drivers.



Arizona, and the Arizona Department of Transportation, decided to keep the metric signage for a few reasons. One reason is that locals have become fond of something that makes the area unique to the nation—it’s something that (aside from the small stretch of I-265) no one else can say they have. Second, business owners claim that they would lose money. Since changing the signs would also change the exits, the shops would be harder to find and they could potentially lose customers. Third, the interstate runs from Nogales to the Mexican border, connecting to I-10, which runs through a major length of the country. This makes I-19 a perfect route for tourists and commerce coming to and from Mexico. Keeping this hour-long drive in kilometers is meant to be a welcome sign for trade and tourists coming from Mexico by keeping signage in their more familiar measurements.


Aside from the historical metric I-19, Arizona is home to a number of scenic highways made for the perfect road trip. The state claims to offer the “most authentic” Route 66 adventure, full of “old diners, vintage motels, and retro filling stations”. Fans of Kerouac’s ON THE ROAD can travel the same route famed by the Beats while also seeing the Petrified Forest National Park, Flagstaff, stopping at Winslow (popularized by the Eagles’s “Take it Easy”), Antelope Canyon, Monument Valley and even one of the best preserved meteor craters in the world. Don’t worry, imperial fans, Interstate Signways makes the mile markers that line the way!


For those in agreement with the I-19 locals, there is still an argument to switch the United States fully to the metric system, but we’ll get more into that next week.

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