This stamp was issued to commemorate the 50th anniversary of the first incandescent electric light, invented by Thomas Edison. Because of the Post Office policy never to portray a living person on a United States stamp, Edison's picture could not be shown on the stamp that honored him. U.S. #656 was the third stamp issued with this design, produced for use in vending machines. This was the first time a commemorative stamp was issued in coil format.