Back before the days of email blasts and tweets, the main form of communication was the post card . These were,( and still are) used for promotional distribution but rarely for personal use. Stores like Denholms would sometimes sell post cards for customers to send back home, letting others know of their travels to Worcester Massachusetts. Of all of the things available via eBay and antique shops, the post card is the most commonly found. The one below of the clown is the face side, and the message is an advertisement of what the Denholm and McKay Co. offered at the turn of the century.
Denholms in 1916
Denholms in 1965