Mail trolley cars included equipment similar to that in Railway Post Office cars. From pigeon holes to sorting racks, everything a clerk needed to process mail quickly was on board. When possible, postmasters added cancelling machines powered by the same electricity that powered the cars.
The cars were owned and operated by rail companies and referred to as RPO trolley cars. Each car was typically staffed by two to four clerks. Mail bags were tossed into the car at post office and train stops. The clerks were responsible for processing that mail, sorting it to stops along the way as well as the final stop.
In addition to the mail clerks, two employees of the trolley company were usually assigned to each RPO trolley car. Mail clerks were joined by the motorman, who was responsible for running the car, and a conductor, who kept the car on schedule and handled the trolley rope and switching duties.