Black Friday is the day following Thanksgiving Day in the United States, traditionally the beginning of the Christmas shopping season. On this day many U.S. retailers open very early, often at 5 a.m. or even earlier, and offer promotional sales to kick off the shopping season. Because Thanksgiving always falls on the fourth Thursday in November in the United States, the day after occurs between the 23rd and the 29th of November.
…Black Friday as a term has been used in multiple contexts, going back to the nineteenth century, where it was associated with a financial crisis in 1869. The earliest known reference to “Black Friday” to refer to the day after Thanksgiving was made in a 1966 publication on the day’s significance in Philadelphia:
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.