This Nov. 1939 envelope from the New York Central (NYC) depicts the first run of the Streamlined Mercury RPO. The RPO (Railway Post Office) was a mail train service that operated on its own dedicated cars. The NYC was one of the most successful RPO carriers in the US. The envelope is in great shape and is a perfect addition for anyone interested in railroadiana and trains. The year of production was 1939 and the item has not been modified.