Next time you find a US special delivery cover in your hands (one from before 1960) be certain you check the BACK of the cover. You very well could see one or even more RPO (railroad postoffice) cancellations. Often they will exhibit two different ones ... I have a couple covers which have THREE and have heard of there being 4 on a single special delivery cover! Kind of neat, no? I have not noticed such treatment on other types of covers. Perhaps postal regs required such treatment for special delivery items. See if your cover can beat three different RPO cancels. Getting good, readable strikes of the RPO postmark is another story but check them out nevertheless.

Mike Cherrington