During the 1920s and 1930s, amateur ham radio operators adopted the practice of two-way exchanging of QSL postcards, to confirm their radio contact, with a report of reception. QSL cards got to be known as wallpaper, commonly used to decorate the walls of their radio equipment room. During the 1960s, CB citizen band radio became popular, and the practice of exchanging QSL cards to confirm radio contacts was enjoyed by many with this new hobby. Many cards have mention of children, refered to as background noise. Some taunt the FCC about then rules and regulations.
About 2005, we bought a very large collection of QSL cards from the estate of the late Henry C. Tadrzenski, KMA-4245, from Bristol, CT. At the time, we looked at them, we sorted them by states, and then re-stored them until now. Henry was an avid user of Citizens Band radio, back in the mid 1960's. He traded bundles of cards with everyone, most times without making radio contact, and accumulated over 15,000 cards. All of the cards appear to be from the same time period, from about 1965-1969. Some cards have a 4 or 5 cent stamp and postmark, and some may just be noted with a date and comments about radio equipment. Some cards have pre-zipcode zone numbers, and some have letters in their telephone number. A few even have notice of their old original CB call sign that was change to the newer assignment, back in the early 1960's. Today, these cards are very collectible and look great matted and framed.