duel tail lights

[fmlondon]

When did duel tail lamps first appear on automobiles? When did they become mandatory?

[woodchopper]

How do you mean dual tail lamps ?

Two bulbs in the one sidelight ?

[fmlondon]

I mean a tail lamp on each side. Early cars had just one tail lamp, whose only purpose was to light the license plate. Sometime, I think, in 1920s, some cars offered tail lamps on each side (as all cars today have), and, I think, sometime in the 1930s, the two tail lamps were mandated.