Arizona Is Home To The Only Metric Highway In The Usa

Perhaps some of you readers may remember back to a time when the U.S. attempted to convert to the metric system? Perhaps you remember using metric units in school or when your high school track was converted to one measured in meters instead of yards. While the 1975 Metric Conversion Act didn’t quite go as planned, you can still find evidence around the country of that attempt. In fact, one prominent example exists right here in Arizona on one of our state’s busy highways.

The open road with long stretches of quiet, rural communities and seemingly untouched wilderness is what draws most people to drive Arizona’s highways. It can be a relaxing, freeing experience especially when the sun is shining just right and you can feel the cool breeze move through the car.

Daniel Ramirez/Flickr

When traveling these roads, this is how our mileage signs typically look. Pretty normal, right?

Doug Kerr/Flickr

Some even just have arrows in lieu of mileage.

Alan Levine/Flickr

But Interstate 19 looks a little different.

Mik Scheper/Flickr

The 63-mile stretch of road links Tucson with Nogales and the Mexican border, this highway also happens to be the only interstate highway in the country with metric distances printed on its highway signs. The reason for this stems from the 1975 act and the highway’s completion in 1979; it only made sense to use new kilometers for a brand new highway than to reprint hundreds of signs for existing highways.

Mik Scheper/Flickr What’s interesting is that the speed limit signs are still listed in miles per hour.

The signs were changed to reflect metric distances and have managed to stay that way even decades after the act was abolished in 1982. In fact, local businesses and residents have prevented changes to the signs, noting the unique identity it gives this small section of Arizona.

Jimmy Emerson, DVM/Flickr

Ken Lund/Flickr

That was pretty cool, huh? If you want to learn more bits of trivia we don’t typically learn in history class, then you’ll want to check out 15 Things You Probably Didn’t Know About The State Of Arizona.