The Penny Goes to War
Copper and zinc, the two metals found in a penny, were rationed during World War II, so the U.S. Mint had to come up with another way to produce its most popular coin. After much debate, the government decided on zinc-coated steel. The steel penny saved enough copper to make 1.25 million shells of ammunition.
The odd-colored penny was manufactured between February and December 1943, but it encountered a number of problems: it rusted, it confused vending machines, and it was frequently mistaken for a dime. In 1944, a new metal combination was selected, and in 1946 production of the original pre-war penny resumed.