Since the origin of the dollar is well documented and understood, one might expect the origin of the dollar sign would also be known. However, this is far from the case and over time, only more theories have been hypothesized. Unfortunately, each theory raises as much speculation as theories about UFOs or BigFoot.
A popular theory referred to by the character Owen Kellogg in Ayn Rand’s “Atlas Shrugged” is that the dollar sign started off as a monogram of ‘US’, used on money bags issed by the United States Mint. Placing the U and the S on top of one another and removing the bottom curve of the U creates the historical double stroke dollar sign.
The Spanish Peso
One of the more widely accepted theories is that the sign owes its origin to the Spanish peso. The peso was the first globally accepted currency and legal tender in the US until 1857. The abbreviation for peso was in the form of a large “P”, and the plural included a small “s” above it and to its right. In theory, this was simplified by retaining the upward stroke of the “P” and superimposing the “S” over it.
If the peso abbreviation is correct, then why is the dollar sign sometimes written with two vertical strokes? The accepted explanation has to do the use of the “Pillars of Hercules” which were engraved on one side of the Spanish peso. The pillars engraved on one side of the coin with the phrase Non Plus ultra meaning “nothing further beyond” (indicating all the land in the world had been discovered) written in a scroll that wrapped around the pillars. But when Christopher Columbus came to America, the engraving was changed to Plus Ultra meaning “further beyond”. Over time, instead of writing out peso or dollar, Americans created a symbol was made from the design on the coins that eventually turned into the dollar sign.
The Portuguese Cifrão Theory
Even though Arabic numbers are used all over the world today, there are still differences in the way in which numbers are represented in different countries. In the English-speaking world a period is used to separate integral numbers from decimal fractions whereas in continental Europe the comma is used instead of the decimal point and either a period or a space is used for thousands and other groups of three digits. In the past the Spanish used a symbol called the calderon to separate the thousands, and the Portuguese used one called the cifrão. As the cifrão was also used to separate numeral expressions of different denominations and it consisted of the letter s with two vertical lines it has been suggested that it gave rise to the dollar symbol. (Über die Herkunft des Dollarzeichens, Christian Weyers, Zeitschrift für Semiotik, vol 13, no. 3-4, 1992).
The Hand Counted Paper Theory
The management of Em Letterpress, a firm based in New Bedford, Massachusetts, pointed out in May 2008 that the dollar sign is used in marking hand counted sheets of paper, e.g. 7$ would indicate seven sheets. Em Letterpress suggested that the most likely reason for that would be that a hastily scrawled ‘S’ would too closely resemble a numeral 5, so ‘SH’ was used, abbreviated over time to an imposed SH, and then the H’s crossbar eliminated resulting in the $ symbol but with a double vertical stroke. Paper money being counted in sheets could have used same symbol.
The Slavery Theory
There have been claims that the dollar symbol, $, is derived from the words for “slave” and “nail” in Spanish (or in Latin, according to one version of this theory that posits an earlier date for the invention of the symbol). The shackles worn by slaves could be locked by a nail which was passed through the rings or loops at the ends of the shackle and bent while it was still hot and malleable. The Spanish for slave is esclavo and for “nail” isclavo. Therefore the “S” with a nail, $, or S-clavo = esclavo or slave.
Slaves constituted a store of wealth and as a result the abbreviation for slaves that slave-owners used in their account books came to represent money.
This seems like the kind of explanation that would be popular with conspiracy theorists. It does not seem to be very popular in printed sources, at least not in English language ones, but I (Roy Davies) have seen it on the Internet and was also told it by someone who said he had heard it from a Latin-American economist and an American history professor.
There are still a handful of theories as to the origin of the dollar sign, but no conclusive evidence that confirms one theory over the other. Although the mystery continues, check out more theories about the origin of the dollar sign here: