Streetcar railway post office (RPO) routes operated in several major USA cities between the 1890s and 1920s. The final route was in Baltimore, Maryland. The Mobile Post Office Society, Affiliate 64 of the American Philatelic Society, has published monographs detailing the operational history of each route. These were cars that had interior fixtures similar to railway-route RPOs. One or two clerks worked in the streetcar RPO to sort mail for post office stations and branches along the route, as well as connecting RPOs that served the city. Cities with streetcar railway post offices Baltimore Boston Brooklyn Chicago Cincinnati Cleveland New York City Philadelphia Pittsburgh Rochester, New York St. Louis San Francisco Seattle Washington, D.C. References Wilking, Clarence. (1985) The Railway Mail Service, Railway Mail Service Library, Boyce, Virginia. Available as an MS Word file at . Mobile Post Office Society (2019) Streetcar RPO monograph set available on CD-ROM including Chattanooga. . United States Postal Service Postal vehicles