1999 55¢ General William “Billy” Mitchell
Pioneers in Aviation Series
Issue Date: July 30, 1999
City: Milwaukee, WI
Printed By: Guilford Gravure for Banknote Corporation of America
Printing Method: Photogravure
Perforations: Serpentine die cut 9 ¾ x 10
Billy Mitchell joined the list of distinguished people honored as part of the Pioneers of Aviation series, which began in 1978. Mitchell is considered the father of the U.S. Army Air Force, the aviation branch of the U.S. Army that became the U.S. Air Force in 1946. The stamp also pictures Mitchell's personal SPAD XVI biplane. The aviator's plane is on display at the U.S. Air Force Museum in Dayton, Ohio.