What was the genesis of the ubiquitous "boxcar red" paint scheme? :?:

Iron oxide is the base pigment, making it the cheapest paint out there for years.

And, back then, the paints were all lead-based. The combination of the lead and iron oxide, made red paint more resistant to rust. And rot.

Paint pigments are traditionally metal oxides and other naturally occurring materials. Iron-oxide red was probably one of the earlier colors, cheap, durable, and probably covered better than many other available pigments. A side note - theoretically if there were true red, yellow, and blue pigments along with pure black and white, the home center paint mixer would only need to have 4 colors to add in to a white base to produce any color possible. The problem is, there is no such thing as a pure yellow, red, or blue pigment.

That makes sense.

Thanks everyone for the info.