Black Friday (shopping) the holiday season, beginning on the day after Thanksgiving. When this was recorded in the financial records, once-common accounting practices would use red ink to show negative amounts and black ink to show positive amounts. Black Friday, under this theory, is the beginning of the period when retailers would no longer be "in the red", instead taking in the year's profits. The earliest known published reference to this explanation occurs in "The Philadelphia Inquirer" for November 28, 1981. In 2013, an internet rumor alleged that the phrase originated in the American south before the Civil War, from the practice of
Common year starting on Friday has only one Friday the 13th; The only Friday the 13th in this common year occurs in August. Leap years starting on Thursday share this characteristic, but also have another one in February. This is the only year type where the "n"th "Doomsday" (this year Sunday) is not in ISO week "n"; it is in ISO week "n"-1. In the (currently used) Gregorian calendar, the fourteen types of year (seven common, seven leap) repeat in a 400-year cycle (20871 weeks). Forty-three common years per cycle or exactly 10.75% start on a Friday. The 28-year sub-cycle does only span across century