Philadelphia police used the terms Black Friday and Black Saturday to describe the traffic jams that occurred the two days after Thanksgiving. This was first reported in 1961 in Public Relations News.
Taking a 'Sickie'
In the 1950s, people began calling in sick the day after Thanksgiving to give themselves a four-day weekend. Since stores were open, those playing hooky got a head start on their holiday shopping.
After making significant outlays buying Christmas stock for their shops, retailers would take the first set of large revenues over the Thanksgiving weekend. This meant many shops would go from being 'in the red' (a loss) to 'in the black' (a profit)
With the popularity of online shopping, internet sites have not wanted to be left out and so Cyber Monday was born and has extended Black Friday into the next week.
Brace yourself, soon it'll be a whole month!