If you still carry coins, you might have noticed a subtle but deliberate design feature: dimes, quarters, and half dollars have rows of narrow grooves along their edges, while pennies and nickels remain smooth. These grooves, officially called reeds, are a relic of a centuries-old battle against theft.
Originally, coins were made from precious metals like gold and silver, and their value was directly tied to the metal content. Dishonest individuals would shave or file small amounts from the edges—a practice known as coin clipping—and sell the scrap while the altered coin continued to circulate at full face value. This problem became so widespread that it triggered The Great Recoinage of 1696 in England, according to Atkinson Bullion.
To combat clipping, mints began adding grooves, lettering, or other markings to coin edges. Anyone receiving a coin could quickly check whether the edge had been tampered with. Pennies and nickels, made from less valuable metals, had little incentive for clipping and thus remained smooth.
Today, U.S. circulating coins are no longer made from gold or silver, so the original security purpose is obsolete. However, the reeded edges serve modern functions. They help people distinguish coins by touch—especially those with visual impairments—since a dime’s ridged edge feels different from a penny’s smooth one. They also aid vending machines and coin counters in identifying denominations by measuring size, weight, composition, and edge characteristics.
According to the U.S. Mint, a dime has 118 reeds, a quarter has 119, and a half dollar has 150. Some dollar coins use inscriptions or other edge markings instead of traditional grooves. The grooves are created during minting: a blank metal disc called a planchet is placed inside a collar as dies strike both sides under immense pressure—between 35 and 100 metric tons of force, depending on the denomination.
While coin clipping has largely disappeared, the ridges remain a small reminder of a time when the metal in a coin was nearly as valuable as its face value. For a deeper look at how coin design intersects with policy, see our coverage of the limited-edition July 4th quarters entering circulation. And for more on how small details can have big implications, check out this analysis of a Colorado socialist’s pledge to reject corporate PAC money.
