Why was the metal in American coins changed for halves, quarters and dimes?

L.A. asks: Why was the metal in American coins changed for halves, quarters and dimes?

The cost of minting a coin has to be below its face value. The difference is called seignorage. This profit is suppose to pay for the cost of manufacturing coins. The Mint currently loses money on the cent (cost 1.8 cents) and nickel (cost 9.4 cents), but the profit on higher denomination coins offsets that considerably. A dime costs only 4.6 cents to produce and the quarter, only 11 cents. I believe the Presidential dollar cost is about 15 cents each.

The rising price of silver in the 1960’s threatened not only seignorage but the economy. Common coins were on the verge of becoming more valuable than their face value so Congress passed laws eliminating precious metals from most circulating coins. This had no effect on the nickel, it was always made from copper and nickel except for a few years during WW II.

Rising copper prices in the late 1970’s caused a similar experience with the cent and by 1982 the cent’s composition had been changed to 99.2% zinc with a .8% copper plating.