According to public consensus:
Math is red (7 votes)
Science is green (6 votes)
English is yellow (4 votes)
History is yellow, tied with red (2 votes)
comments (single view)
No, that is the most silly idea I have ever heard, history’s not anything particularly important, so why give it the most known color??
think about how much blood has been spilled throughout history and maybe that will change your opinion. 
Still the main color, it doesn’t make sense not to assign it from the beginning on
clearly you’re outnumbered (only history agrees with you), so maybe history is red for most people…
That’s the first color that comes to mind when thinking color for most people
most people where? in Germany, in the U.S., in Asia, in the whole world?? saying a color “is the main color” doesn’t make sense.