Tom P. asks: Why do American coins such as the dime, quarter, half dollar, and silver dollar have reeded edges and the penny and nickel do not?
Reeded edges were incorporated into precious metal coins to prevent filing, that is removing a small amount of metal off a coin that cumulatively would be sold. Money used to be defined as precious metal in coin form. Reducing the weight of a coin would render the coin’s value less than its face value. By examining the reeded edge a prospective receiver of the coin could ascertain that a coin hadn’t been filed. This saved the trouble of weighing it. Cents and later nickels were convenience items that had little or no legal tender status, had no precious metal and therefore there was no reason for them to have a reeded edge.
Though today’s circulating coins have no precious metal content, the tradition of plain and reeded edge coinage continues.