Canadian National Railway mail car

The photo was taken by Robert K. Lane at the Edmonton Railway Museum.

Railway Post Office (RPO) and Transportation Post Office (TPO) postmarks have attracted many philatelists interested in postal history, railway history, and waterway history.

The railway mail service began operating in 1854 when mail was sorted by postal clerks while being carried in railway cars travelling from town to town along rail routes. The service grew rapidly, and the Post Office Department created the Railway Mail Service Branch in 1897. The railway mail service peaked in the 1950s, and ended with the last railway mail car run on 24 April 1971.

During the almost 120-year operation of the railway mail service, there has been an overwhelming number of RPO postmarks, hammers, and routes. Fortunately, early collectors diligently documented their findings for the benefit of later enthusiasts.

In December 1972, Lewis M. (Lew) Ludlow wrote the first of his 101 "RPO Cowcatcher" columns in BNA Topics. The popularity of the column was such that, when Ludlow gave it up for health reasons, it was continued by William G. Robinson, Brian T. Stalker, Peter McCarthy, and others.

The RPO Study Group was formed at the 1973 BNAPS convention in Calgary. Lew Ludlow volunteered as Chairman and editor of the RPO column in BNA Topics and Jim Lehr as Secretary-Treasurer and newsletter editor. By 1 January 1974, the Study Group had 28 members.

The Study Group has been active since its formation, and has published over 250 issues of its award-winning newsletter.