Existing comment:
R IS FOR RAILWAY POST
A Railway Post Office {RPO} was a special mail car on a train.
From the 1860s until the 1950s, most intercity mail in the U.S. was postmarked and sorted by hand en route in these cars.
While a train was still in motion, RPO clerks used a long hook to pick up mailbags hung on special track-side poles.
The last true RPO made its final trip between Washington D.C. and New York in 1977. |