Billboard cars

[nw-mailing-list at nwhs.org]

The reason for the exemption was that the cars with special equipment 
could only be used by one shipper or one commodity.  The cars usually 
were owned by that shipper  and not in general revenue service.  There 
was no reason to ban advertizing on cars that weren't in general revenue 
service and available to all shippers.

Hope this helps

Larry Smith