Where Did the Dollar Sign Come From?
No one really knows where the dollar sign ($) came from. The probable explanation is that it comes from the design stamped on the old Spanish “piece of eight.” One side of this coin was marked with the shapes of the two Pillars of Hercules. A ribbon winds around the pillars.
Before Americans had their own dollar, they used this Spanish coin for a dollar. For its symbol, they drew an S-shaped figure crossed by two bars representing a ribbon winding around two pillars. When the United States made its own dollar, the symbol for it was that of the old piece of eight.
Some scholars theorize that the $ sign evolved out of an abbreviation for peso: The plural for pesos was “ps,” which eventually became “ps,” and then simply an “S” with a single stroke denoting the “p.”
One early instance of the $ symbol crops up in a letter written by the merchant Oliver Pollock in 1778. Pollock also uses the “ps” abbreviation, making the letter a bridge between the two. The double-line through the S variation is less easily explained.