When did they start putting the blue lines on downhill skiing courses?

Question

When did they start putting the blue lines on downhill skiing courses?

Answer 1

Blue lines have marked the edges of the course in slalom and giant slalom for as long as I can remember.

It's the blue lines across the tracks (every 10m or so I guess) which are rather new(ish).

Answer 2

We used them in the 1960's on slalom  courses just evolved to downhill. The lines are for depth perception at speed.  60 MPH in  flat light is just plain dangerous and the racers know better than to risk their bodies.