Origin of the $ Sign
The origin of the "$" sign has been variously accounted for. Perhaps the most widely accepted explanation is that it is the result of the evolution of the Mexican or Spanish "P's" for pesos, or piastres, or pieces of eight. This theory, derived from a study of old manuscripts, explains that the "S," gradually came to be written over the "P," developing a close equivalent to the"$" mark. It was widely used before the adoption of the United States dollar in 1785.