Quote Originally Posted by pomtzu View Post
It is both, Karen, and originally it was in reference to the heavy pedestrian and vehicle traffic on that day - the start of the holiday shopping season. It originated in Philadelphia in the 60's and spread, and eventually took on it's other meaning of the profit/loss scenario.
I heard a story today on NPR - Black Friday was a term in the 1950s - when factory managers called it "black friday" because so many people called in "sick" that day, they compared it to the "black death" - a.k.a. the bubonic plague. Then in the 1960s, it was adopted by the Philadelphia police as you mentioned, the 1970s it became the financial meaning I mentioned, and in the 1980s it transformed into the shopping event it is now, and was adopted by retailers as a positive connotation and name for sales.

So we were both wrong as to how it originated, and both right in a way, we just didn't know about the first usage!