Just for general info, what the ICC banned as far as bill boards were concerned was that the bill board had to advertise only what was carried in the car. The result was that the railroads no longer could put advertising on the cars because they used the reefers for all sorts of loads and for different customers. After the ban was put in place, the only bill board refers still operating were the meat packer's reefers because they were all privately owned.
It's amazing how this myth continues on that the railroads leased out advertising space on their cars. wall1 It basically comes from a misunderstanding of how cars were owned or leased.
100+ years ago the cars were owned by the railroad, and leased to the company that wanted to use it. That's why you find pics of old cars with both the railroad's name and the company's name on it. The company is the lessee, they didn't just pay to put their ad on the side of the car. They were called Billboard reefers because they used big lettering on the side, like a billboard sign, not because they were paid advertisements like billboard signs.
Later the government (I believe during Theodore Roosevelt's administration) ruled that the railroads had a monopoly re refrigerator cars, so the railroads set-up related but technically separate companies. Some were owned by several railroads, like Fruit Growers Express or Pacific Fruit Express, some worked with just one railroad like Burlington Refrigerator Express (CB&Q), Western Fruit Express (GN) etc.
BTW leased cars can be spotted by their reporting marks which always end in "X". BREX doesn't mean Burlington Refrigerator EXpress, the BRE is the company name and the X indicates it's a leased car.
Anyway, the problem the railroads got into is they would get a call to deliver a reefer to ABC packing co., and the first one they had iced up and ready to go was lettered for XYZ co. ABC packing would refuse to use the car, not wanting to pay to send a car across country as a rolling advertisement for their competitor. So, the RR would have to go get another car.
The ICC ruling in the 1930's said lettering on cars not used in captive service could only be so large (IIRC something like 16" high letters?) and couldn't have big graphic etc., and that the cars then had to be accepted as interchange by any company...ABC packing couldn't refuse an XYZ co. car, or if they did, they had to reimburse the RR or some such deal.
So I know some folks like to think about that evil "gubmint" restricting business and all that, but really the rule against billboard cars was more a case of government regulation helping an industry (the railroads). :mrgreen: