So where did the use of the term Black Friday come from? Like many other slang terms, there isn’t really a definite answer. However, two possibilities exist:
In Philadelphia, where the sales originated, police deemed the retail event Black Friday because the amount of traffic was a black spot on their holiday weekend.
The more popular explanation has to do with the colors of ink accountants traditionally used for noting profit and loss. A company “in the red” is recording loss. “In the black” means just the opposite. Since many retailers report some of their highest profits on Black Friday, the black portion of the name, "Black Friday" relates to businesses recording higher profits. This tradition, of course, lives on in modern accounting software.