A road sign from Arizona:
Came across this from the web, found it curious. Traditionally the US, Burma and Liberia, I believe, don't use metric. But there are metric road signs in Arizona?
Congress passed the Metric Conversion Act in 1975, the last time the US had a serious metric system push, and various tests were carried out to start the conversion process. I-19 in Arizona was one of the test sites. After widespread opposition ("Forcing the American people to convert to the metric system goes against our democratic principles" is a quote from Chuck Grassley in 1977, and the guy has not mellowed out since then), the Metric Board was eventually disbanded.
Our bosses at the Arizona Department of Transportation have tried to change I-19's signs back to miles before. The signs have to be replaced periodically anyway. But businesses along the highway say doing so would make their shops harder to find, since the exit numbers would also change.
They tried to change the signs back to miles as recently as 2009, but there was local opposition that put the plan on hold. The issue came up again in 2014, still without any change.
Appears as though it was a timing situation when it was built, during a brief law change.
That made sense in 1980, when I-19's signs first went up and when US was near the peak of its flirtation with the metric system. Five years earlier, President Ford had signed the Metric Conversion Act, declaring the metric system "the preferred system of weights and measures for United States trade and commerce" and establishing United States Metric Board to guide the conversion. Schoolchildren dutifully learned their kilograms and centimetres.
But the Metric Conversion Act was only voluntary, and there was far too much inertia to change every single label in the country voluntarily. Reagan disbanded the Metric Board in 1982. Instead of leading the charge into brave new metric system, Arizona's highway is a reminder of a failed experiment.
I'm willing to bet that this sign is from a place close to the Mexican border. I live in San Diego, CA, a city close to the Mexican border, and I've seen a few road signs in my area with metric units (actually, both metric and Customary units).
The reason why those metric signs exist is because frequently, people driving on those roads are often tourists from Mexico, driving cars that were built for the metric system (speedometer and odometer measure in metric units). This sign was put up for the benefit of people who are driving such cars, especially older cars that lack alternate scales for the Customary system.
You might even see similar signs in places close to the Canadian border, especially in areas frequented by Canadian tourists.