This turned up on C-SPAN today. A 1956 USPS training film for new Railway Post Office employees, showing a trainee making his first run on a RPO car, on the B&O from Washington Union Station West. I recognized Union Station, Harper's Ferry, WV and Cumberland, MD. I'm guessing someone here can make out a couple of other locations. One of them might be Shenandoah Jct. Anyway, a fascinating look at a bygone profession. The film also briefly mentions and shows a Highway Post Office truck/bus. Any of our readers from across the pond would find the comparison with a Royal Mail Traveling Post Office interesting, especially the differences in dropping and receiving mail "on the fly".

Link: https://www.c-span.org/video/?475210-1/men-mail-transit

Thanks for posting the link to that interesting film. I didn't know anything about the roadway "sorting office" bus operation in the US either.
For picking up mail "on the fly" the US system looks a lot more simple than the UK version, though I think our "drop off" version is more predictable/accurate than the US "sling it out the door" mail transfer!
For those who havent seen the UK versions, this film on the GCR shows it in detail..
https://www.youtube.com/watch?v=stIh4RweYns

A friend and neighbor was an RPO Clerk from the 1930's to the end June 30, 1977-July 1, 1977. Initially (Amtrak Day, May 1, 1971) the trains had four RPO's each but by 1977 each side had two full 60-foot cars.

As it happened, his crew was off the week of the final trip (the NY & Wash crews worked 6-day weeks, 2 on and 1 off) but the commemorative West/Southward train included an Amtrak lounge car and he could be found there.

Amtrak did not then have authority to carry the mail so trains 3 & 4 were Penn Central, then ConRail trains operated by Amtrak under contract. For the last trip, someone wanted to paint one of the cars but the shop was not authorized to paint it ConRail, so in 1977 they painted the car as Penn Central! It was a typical PRR BM70MA car, 70 feet long with a 60 foot mail apartment leased by the Post Office and a 10 foot "bungalow" for railroad use.

Power for the commemorative train was GG1 4935 in PRR pinstripes.

Here are drawings of a PRR BM70MA car. BM70NA was similar but with a lower roof.

http://prr.railfan.net/diagrams/PRRdiag ... &sz=sm&fr=

http://prr.railfan.net/diagrams/PRRdiag ... &sz=sm&fr=

Phil Mulligan

I believe the shot of the bag hook up was filmed at the Dickerson, MD B&O station on the Metropolitan Branch northwest of DC.

To clarify something you see on the side elevation of the BM70MB, the four panels on either side of the narrower mail doors are steel castings so when the crew catches a pouch of mail on the fly from the mail crane, the panel spreads the impact so the side of the car is not damaged.

Phil Mulligan