Many decades ago, all coins were made from solid gold or silver. The amount of metal used in the coin was equal to its value ($10 of gold in a $10 gold coin, etc.) Before coins’ edges had ridges, dishonest people would shave off small amounts of metal form the sides of coins, keeping a valuable collection of shavings before depositing their coins in the bank. By milling the edges of the coins, the U.S. Mint made it impossible for thieves to steal metal shavings without removing the familiar texture.
Want to know more about the money we use everyday? Check out the U.S. Treasury’s Bureau of Engraving and Printing website at www.moneyfactory.gov.