I just read a bit more about Black Friday on Wiki and I guess the name may have originated in Philadelphia due to high auto and pedestrian traffic.
JANUARY 1966 -- "Black Friday" is the name which the Philadelphia Police Department has given to the Friday following Thanksgiving Day. It is not a term of endearment to them. "Black Friday" officially opens the Christmas shopping season in center city, and it usually brings massive traffic jams and over-crowded sidewalks as the downtown stores are mobbed from opening to closing.
And later they used the definition I posted above (also supposedly originated from Philly)
Also interesting, supposedly the term became more popular around the US back near 2000 and prior to that it was more of an east coast thing. I wouldn't know though because I've always known about Black Friday probably because we always went down to Philly for Thanksgiving.
