billboard cars

[nw-mailing-list at nwhs.org]

This may be a bit "off-topic", and if so I apologize.

I have seem numerous references to the ICC outlawing billboard sides on box cars and refrigerator cars.  Mostly I've seen references to mid 1934 for deadline to no longer repaint these billboard sides, and 1937 to outlawing them for interchange.

Does anyone have any information as to the reasoning behind this decree?  I can't see how a colorful paint job affects safety.  There wouldn't be any difference in how these cars are required to be returned to the originating road than any other.

John Samples