dollar sign

dollar sign, $, symbol that represents the dollar, the name of the standard monetary unit used in the United States, Canada, Australia, New Zealand, and a number of other countries and territories. The dollar sign is also used for several currencies that use different names, including the Brazilian real, the Mexican peso, the Nicaraguan córdoba, and the Macanese pataca.

The dollar sign takes as its base the form of the capital letter S. A vertical line bisects the S. Less commonly, two vertical lines are used in place of one.

Outside of currency, the dollar sign is used as a common sigil (symbol for a variable) in many computer programming languages, including Beginner’s All-Purpose Symbolic Instruction Code (BASIC) and several scripting languages such as Perl. In BASIC, the symbol is suffixed to a variable representing an array, or collection, of strings; in scripting languages, it is typically prefixed to a variable with scalar, or single, value.

The origin of the dollar sign is a matter of debate. The most widely circulated theory asserts that it originated as a symbol representing the Spanish milled dollar (also called peso). After the United States gained independence in the late 18th century, it created a new currency based on Spanish coinage, the most common coin in circulation in the colonies. The United States’ first dollar coins, minted in silver in 1794, not only took their name from the Spanish dollar but also borrowed the Spanish dollar’s weight and value. Because of the close connection between the two currencies, it is likely that if a symbol existed for the Spanish dollar before 1794, it would have been used for the U.S. dollar. The earliest known occurrence of a dollar sign in print, however, was in 1797.

According to a related theory, the symbol stems from an abbreviation of peso as Ps. The strongest support for this theory comes from a 1778 invoice handwritten by Oliver Pollock, a financier of the American Revolution, in which the P in the Ps abbreviation appears to be superimposed on the s, thereby bisecting it. Despite the resemblance between Oliver Pollock’s handwriting and the dollar sign, however, there remains little evidence to suggest such a symbol was in contemporary usage or that Pollock’s possible slip caught on.

Another theory relates to the origin of the Spanish dollar itself. When Spain underwent a coinage reform in 1497, the dollar was introduced as Spain’s unit of currency. Its full name was peso de ocho reales (or “piece of 8 reales”), and, as its name suggests, it was worth 8 units of the real, the former standard. Some have therefore speculated that the $ symbol arose as a stylistic variation on the Arabic numeral 8, although no documents have surfaced that demonstrate 8 being used to symbolize the Spanish dollar.

The peso originated during the reign of Ferdinand II of Aragon (1479–1516), and some see a resemblance between one of his royal symbols, which was cast on the bill, and the dollar sign. After Ferdinand’s forces gained control over the Strait of Gibraltar, he added to his coat of arms two columns representing the Pillars of Heracles, wrapped with a ribbon. Many people suggest that the bar in the dollar sign resembles one of the pillars, while the S looks like the ribbon. There is little evidence, however, to indicate that the dollar sign came from the $-like representation of the pillars on the Spanish dollar.

The lack of evidence behind the dollar sign’s historical development has allowed room for folktales. Among the most well known is that promulgated by Ayn Rand in her novel Atlas Shrugged (1957). In it she asserts that the symbol is an amalgamation of the letters U and S (representing “United States”) with the bottom of the U dropped. The literary merit of this claim lies in representing the U.S. as a bastion of economic freedom, but it has no factual basis.