During the earliest days of radio, listeners enjoyed trying to tune in distant stations. These "DX" listeners would send reception reports to the station hoping to receive the station's EKKO stamp, which would be glued into a special album. The samples to the left are early EKKO stamps for WPAJ and WDRC.

The sample on the right was issued by the Bryant Company in the early 1930s.

Sometimes stations would send form letters confirming reception, like the one below mailed to G.E. Jacques in Hornell, NY on December 1, 1931.

Cards were out and letters were in when this QSL was issued in 1947.

Here is the same card, signed by two different chief engineers (1966 on the left, 1970 on the right).