There are several theories. The first suggests that the term derives from an accounting reference to profitability. Stores operate at a loss, or are �in the red�, until the day after Thanksgiving, when sales skyrocket and they turn a profit, or are �in the black�. Another more precise explanation dates back to the early 1960s, when police officers in Philadelphia began using the term �Black Friday� to describe the chaos created by the large number of shoppers that would flock from the suburbs to the city to do their Christmas shopping.