why are barns redWhy are barns typically painted red?

Is there a reason? The only barns I ever see are red, why not blue or something?
At this point, it's more tradition than anything. But historically, there are a few reasons:

"Centuries ago, European farmers would seal the wood on their barns with an oil, often linseed oil -- a tawny-colored oil derived from the seed of the flax plant. They would paint their barns with a linseed-oil mixture, often consisting of additions such as milk and lime. The combination produced a long-lasting paint that dried and hardened quickly. (Today, linseed oil iswhy are barns red sold in most home-improvement stores as a wood sealant). Now, where does the red come from?

In historically accurate terms, "barn red" is not the bright, fire-engine red that we often see today, but more of a burnt-orange red. As to how the oil mixture became traditionally red, there are two predominant theories:

Wealthy farmers added blood from a recent slaughter to the oil mixture. As the paint dried, it turned from a bright red to a darker, burnt red.

Farmers added ferrous oxide, otherwise known as rust, to the oil mixture. why are barns redRust was plentiful on farms and is a poison to many fungi, including mold and moss, which were known to grown on barns. These fungi would trap moisture in the wood, increasing decay."
http://people.howstuffworks.com/question635.htm

Also my dad told me once that the paint used to paint the wood to keep away bugs and stuff was just..red.
Cause of the stuff in it, I guess? not sure if he was right.
Because it's the cheapest way to make decent paint. the red color is from iron oxide, good old rust.
I've seen blue barns before.