There ' s a number of things it comes from . There ' s a memetic link to Black Tuesday , a stock market crash on October 29 , 1929 that was so bad it got its own special name for the day . There ' s the habit of workers calling in sick on the Friday immediately following Thanksgiving , in numbers so large that if epidemiologists took it seriously they ' d see similarities to the black plague . Then Philadelphia police in 1951 called it black friday to describe the despairinducing traffic congestion every year on the Biggest Shopping Day of the Year . It ' s a multifaceted thing , influenced by a number of events , though from personal experience I can assure you that it ' s only gained a general happynote connotation in the past decade or two , associated with special sales . The blackness is a signal of woe and misfortune .