TRIVIAL PURSUITS: What Is the Origin of the “Dollar” Symbol

What is the origin of the $ -- the symbol for “dollar?”

In the pioneer days, the symbol for currency was “US.” The “S” was placed directly over the “U” and in time, was shortened by writing an “S” with two lines through it.  

We’ve gotten even lazier, as now the common symbol is an “S” with one line through it.