During World War II, the United States Mint produced coins made from a different composition than usual because of the shortage of copper. Therefore, the coins are made of 35% silver, 9% manganese and the remaining 56% copper. Wartime nickels are identifiable by the large mint mark on the obverse (heads side) of the coin located under the date and above the Monticello building.
The mint marks used were:
* P - Philadelphia Mint
* D - Denver Mint
* S - San Francisco Mint
Wartime nickels are more valuable than regular nickels because they contain silver. While their melt value has fluctuated over time, due to the price of silver varying, you can expect to get several dollars for each of them.