This postcard from Weehawken resident John Strole of Cooper Place, reported that he had received a short wave radio signal from radio CX in Belgium in 1948. Reception reports like this provided short wave stations with information on how their signals were propagating and provided a hobby for collectors - the receiving station generally sent back a souvenir postcard to the reporter.
For more information on QSL cards, see https://en.wikipedia.org/wiki/QSL_card