Pass plate

[Roland Koster]

Hi there, that's an interesting theory. I always thought they were used so people knew which side to pass. Because the English and Canadian weren't used to drive on the right side of the road. Also when approaching vehicles on desert roads is sometimes difficult to see/understand at which side the upcomming vehicle will pass.
It's only a theory though. (p.s. I do have an original (from stock) pass-sign holder. I got it years ago from Canada.)

I wonder if there's a theory which can be confirmed...

Roland