Here in Michigan and much of the Midwest, most barns are red. Why? To me it makes sense for them to be white, but there they are. Red barn after red barn. Please Register or Log in to view the hidden image! Please Register or Log in to view the hidden image! Please Register or Log in to view the hidden image!
You know Orly, that's a good question. I grew up in Ohio, and barns are red - that's it, they're just red - period. I am as interested in this answer as you, but I suspect it may just be a matter of tradition or somesuch. I must admit that I did see the occasional and I mean very occasional white barn back then. For some reason, these tended to have green trim... Please Register or Log in to view the hidden image!
Perhaps because the farmhouse was not packed to the rafters with bales of vegetation absorbing moisture & didn't have a gaggle of animals crapping all about the place - not to mention being at least somewhat climate controlled - there wasn't the fungoid growth problem that a barn might suffer. Maybe the red barn/white farmhouse combo originated with immigrants from the German state of Hesse who were duplicating the colors of their flag: http://www.german-flag-history.com/hesseflag.html White/green combo could have been people from Saxony: http://www.german-flag-history.com/saxonyflag.html Sounds a bit silly, I admit - but people are insane. Please Register or Log in to view the hidden image!
Cheap, long lasting anti-fungal pigment - red lead and then iron oxide. Paint your house that colour and it will get much hotter in the summer than if you painted it white, which was lead carbonate and zinc oxide then, titanium oxide and zinc oxide now. Still pretty cheap. There are plenty of houses painted that colour in Detroit. Please Register or Log in to view the hidden image!
Here is an article: Why are barns usually painted red: 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. Rust 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.
