Before the current technology of highly reflective tape, and other 21st century materials, were used to make the road signs along the nation’s highways, we had letters called “Button Copy”. These are metal or ceramic letters with reflectors embedded in the letter, approximating the shape of the letter when illuminated by vehicle headlights.
Lots of folks will say the technology is outdated because new nEW NEW is always better (a 21st century attitude if I ever heard one), but in actuality, button copy signs had a shelf life measured in decades, while today’s signs are expected to last one decade. Original signs did not use reflective backgrounds, only the message legend was illuminated, but back in the 80s some in the U.S. government decided the color of the sign needed to be reflective as well, and that’s when button copy began to struggle a little bit. Signs were actually a little too bright when designed to be completely reflective, and the button copy was washed out by the rest of the sign panel.
ADOT can’t decide whether they’re going to get rid of the metric signs along Interstate 19 and convert the whole road to the inferior English Units. The roadway was built when the United States was strongly considering moving the metric to come up to speed with the rest of the world, but then Reagan was elected to office and we began the whole “‘Merica!!!” movement and for some reason the metric system became associated with the devil and conspiracy theories.
ADOT did replace all the metric signs with new metric signs in the late 1990s, some of the last “button copy” signs to be installed in the United States. Many of these signs stand today and aren’t doing too bad in the reflectivity department for being over 20 years old.
The sign on the left lost its Interstate 10 route marker years ago. I don’t know why it wasn’t ever replaced, probably because the sign was going to be replaced and then they couldn’t decide if they were going to keep the metric system on the roadway or not so it just stays there missing.