The Centuries-Old Reason Your Quarter Has Those Tiny Ridges

It turns out the grooved edge on your dime is not a design quirk — it is a 300-year-old anti-fraud measure that the U.S. Mint still relies on today.

Dimes, quarters, and half dollars carry reeded — grooved — edges as a defense against coin clipping, the practice of shaving metal from a coin's rim and passing it at full face value.
The technique dates to the era when American coins were struck in silver and gold, metals valuable enough to make clipping worth the criminal risk.
Pennies and nickels were historically spared the ridges because their base metals offered little incentive for clipping.
The U.S. Mint inherited the reeding practice from earlier European coinage traditions, including reforms associated with Sir Isaac Newton during his tenure at England's Royal Mint in the late 1690s.
Modern coins no longer contain precious metals, but the reeded edge survives — partly tradition, partly a tactile aid for visually impaired users distinguishing coin denominations by touch.

Take a dime out of your pocket and run a thumbnail across the edge. Those tiny parallel grooves — 118 of them on a standard U.S. dime, if you have an afternoon to count — are not there for grip or aesthetics. They are there because, for a long stretch of monetary history, people were shaving coins for profit and someone had to stop them.

The practice was called clipping: slice a thin ring of silver or gold from a coin's rim, pocket the shavings, and spend the lightened coin at full face value. Do it enough times and you had yourself a tidy side income at the expense of whoever ended up holding the short coin. By the time colonial America was minting its own currency, clipping was enough of a problem that the solution was literally baked into the design.

Reeding — the technical term for those edge ridges — made the fraud immediately visible. A clipped coin would arrive smooth where it should be grooved, and any merchant paying attention would turn it away. The approach had roots in European reform coinage, with England's Royal Mint pushing the technique aggressively in the late seventeenth century under the oversight of, among others, Sir Isaac Newton, who took the Mint's fraud problem surprisingly seriously for a man better remembered for gravity.

Pennies and nickels never got the treatment because copper and nickel simply were not worth the effort. Nobody was shaving Lincoln cents for profit. The same logic holds today — contemporary quarters contain no silver at all — but the ridges remain, now pulling double duty as a tactile marker that lets visually impaired users distinguish a dime from a penny by feel alone.

The U.S. Mint has not announced any plans to change the edge design.