According to Wikipedia the origin of the name has been traced back as far as the 1960’s. The name of Black Friday was first heard of in Philadelphia as people described the amounts of heavy traffic and the smog produced on that day. It always takes place the Friday after Thanksgiving day and it signals the beginning of the Christmas season. During this day retailers offer their products at a discount and consumers find it as a great opportunity to buy Christmas gifts early in the season.
http://en.wikipedia.org/wiki/Black_Friday_(shopping)
