The red line itself.

[SHINEdown30]

This may be spam I'm not sure. But why is this called the red line. Why not the blue line, since its used often in hockey. You have the huddle for football.....nothing but net for bball. Everything associates with its name to its sport. I can see Red light, for the goal or blue line or even the faceoff. But why redline? Is it because the faceoff starts the game and thats on the redline?