United States quarters and dimes feature tiny ridges along their outer edges because historical coins were minted from solid silver and gold, making them prime targets for a highly lucrative scam known as coin clipping.

A coin’s edge was part of its security

In a precious-metal coin, the face value depended on the metal inside it. A dishonest holder could shave a thin sliver from the rim, keep the coin in circulation, and collect the removed metal. One coin yielded little, but repeating the trick across many coins could turn small losses into a profitable scheme—and leave everyone else holding underweight money.

Mints countered this by putting a regular pattern of grooves, called reeding, around the edge. The grooves gave people a quick way to spot tampering: clipping interrupted the pattern or made the coin’s edge look uneven. The rim thus acted as a visible seal, helping merchants and customers judge whether a coin still contained its intended weight without weighing every payment.

Why the ridges outlasted the silver

Early U.S. dimes and quarters were made with silver, but the precise metal content and composition of American coins changed over time. Reeding remained useful as a familiar security feature and as a way to distinguish denominations by touch and appearance. On today’s coins, it no longer guards a valuable silver rim; it is a design inherited from an era when the edge itself could reveal theft.

That small detail reflects a larger economic problem: money works only when people can trust that a coin accepted at face value has not been secretly diminished. The ridges made that trust easier to check in the hand.