<P> With the entry of the United States into World War II , nickel became a critical war material , and the Mint sought to reduce its use of the metal . On March 27 , 1942 , Congress authorized a nickel made of 50 % copper and 50 % silver , but gave the Mint the authority to vary the proportions , or add other metals , in the public interest . The Mint 's greatest concern was in finding an alloy that would use no nickel , but still satisfy counterfeit detectors in vending machines . An alloy of 56 % copper , 35 % silver and 9 % manganese proved suitable , and this alloy began to be coined into nickels from October 1942 . In the hope of making them easy to sort out and withdraw after the war , the Mint struck all `` war nickels '' with a large mint mark appearing above Monticello . The mint mark P for Philadelphia was the first time that mint 's mark had appeared on a US coin . The prewar composition returned in 1946 ; all nickels struck since then have been in 75 % copper and 25 % nickel . </P>
<P> With the entry of the United States into World War II , nickel became a critical war material , and the Mint sought to reduce its use of the metal . On March 27 , 1942 , Congress authorized a nickel made of 50 % copper and 50 % silver , but gave the Mint the authority to vary the proportions , or add other metals , in the public interest . The Mint 's greatest concern was in finding an alloy that would use no nickel , but still satisfy counterfeit detectors in vending machines . An alloy of 56 % copper , 35 % silver and 9 % manganese proved suitable , and this alloy began to be coined into nickels from October 1942 . In the hope of making them easy to sort out and withdraw after the war , the Mint struck all `` war nickels '' with a large mint mark appearing above Monticello . The mint mark P for Philadelphia was the first time that mint 's mark had appeared on a US coin . The prewar composition returned in 1946 ; all nickels struck since then have been in 75 % copper and 25 % nickel . </P>
when did nickels stop being made of nickel
when did nickels stop being made of nickel
1942
1942