Whilst the origins of the term ‘Dollar’ and its transformation to common usage in the US appear to follow a well laid-out path. The evolution of the $ sign itself is somewhat more uncertain. There are a number of competing theories, each of which are seemingly possible, though some with more credence than others.
The most likely is the theory that it comes from a handwritten ‘ps’, an abbreviation used in correspondence as a plural form of ‘Peso’. Manuscripts from the late 18th and early 19th century show the ‘s’ gradually being written over the ‘p’, and the upward stroke of the ‘p’gaining dominance over the curved upper part. This eventually developed into something resembling the ‘$’ sign. (see below)
The most likely is the theory that it comes from a handwritten ‘ps’, an abbreviation used in correspondence as a plural form of ‘Peso’. Manuscripts from the late 18th and early 19th century show the ‘s’ gradually being written over the ‘p’, and the upward stroke of the ‘p’gaining dominance over the curved upper part. This eventually developed into something resembling the ‘$’ sign. (see below)
The ‘ps’ symbol first occurs in the 1770s, in manuscript documents of English-Americans who had business dealings with Spanish-Americans, and it starts to appear in print more commonly after 1800. – This does not however explain why sometimes the $ sign is drawn with 2 lines running through it.