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
Friday the 13th year being a common year starting on Tuesday (F) (e.g. 2001/02, 2012/13 and 2018/19), or from August to October the following year being a leap year starting on Saturday (BA) (e.g. 1999/2000 and 2027/28). The shortest period that occurs with a Friday the 13th is just one month, from February to March in a common year starting on Thursday (D) (e.g. 2009, 2015 and 2026). Each Gregorian 400-year cycle contains 146,097 days (with 97 leap days) or exactly 20,871 weeks. Therefore, each cycle contains the same pattern of days of the week and thus the same pattern of Fridays that