This six-cent U.S. stamp was issued in 1968 and commemorates the 100-year anniversary of the Benevolent and Protective Order of Elks and its youth programs.
The National Postal Museum, operated as part of the Smithsonian Institution, has an amazing online database of U.S. stamps, called Arago. The database page for this 1968 issue provides the following historical information:
"The 6-cent Support Our Youth commemorative postage stamp was issued on May 1, 1968, at Chicago, Illinois, during National Youth Week, which was sponsored by the Benevolent and Protective Order of Elks. The stamp was available at other post offices as fast as manufacturing facilities permitted, but there was some delay.
"In observance of its centennial that year, the BPOE extended its youth service program. One activity was a massive job hunt in some 2,100 communities to uncover summertime and part-time employment opportunities for young people.
"The stamp was designed by Edward Vebell of Westport, Connecticut, and was issued in panes of fifty, with an initial printing of 120 million."
Now, 47 years later, I'm using one of these stamps to send a York Fair postcard to a fellow Postcrossing user in Minden, Germany.