Why are gas cans always red in color?

Question

You never see a blue or a green gas can. I'm talking about the kind of can you use when your car runs out of gas

Answer 1

I was always thought red was for gas, green was for diesel and blue for kerosene.  

Answer 2

the red on the can is a chemical warning for flammable material

Answer 3

I guess that its a kind of warning

red usually isn't a very positive color, like a stop light??