A 5-cent stamp celebrating the Sixth International Philatelic Exhibition was issued on May 21, 1966, the opening day of the exhibition, which was held at the Shoreham Hotel in Washington, DC, May 21 through May 30, 1966. A 5-cent souvenir sheet, designed by Brook Temple, was also issued on May 23rd.
Designed by Thomas F. Naegele of New York, New York, the stamp was issued in panes of fifty and printed on the Giori press. It was authorized for an initial printing of 115 million.
Postal Bulletin (April 28, 1966).