As you could probably tell, I was driving a bit recently, and once in a while saw this kind of a sign, often equipped with a (beloved) segmented font, reporting your current speed as detected by radar:

Just today, I learned of an early version of this idea:

This was a “Speed-Minder” deployed by Illinois State Police in the late 1950s or early 1960s. The car didn’t have a radar, it just reported its own speed, which I thought was clever. I am not even sure if it was as much to prevent drivers going too fast – I guess that’s what the name suggests – or just to help you calibrate your car’s own speedometer.

I can’t find a lot of information whether this was effective in any way, but I just liked this visual of a non-digital speedometer mounted atop an old police car.

Before Pixels is an occasional foray into design ideas before screens came around, shared for context, amusement, and inspiration.