When was the two line pass rule implemented? Was this a rule the NHL adopted at some point down the line, or was it present from the earliest days of the game? If so, when was that rule dropped by the IIHF, amateurs, and college hockey?
I know that the red line was dreamed up in the 1940's to speed the game up and prevent opponents from stacking the blue line with players. It worked like a dream. That's why I always laugh when people suggest taking it away. There's a fine historical rendering of this situation in Ken Dryden's marvelous book, The Game.