The folks over at the Foundation for Economic Education have provided us with a nice little background on why "Black Friday" is called that.
If you don't have time to read the story before you head out on your post-Thanksgiving shopping binge, here are the three competing theories behind "Black Friday."
1) National Hooky Day
Black Friday was the 1950s equivalent of Monday after the Super Bowl. Everyone just called in sick. As a result, productivity tanked. Nobody really knew what to do about it, which is probably why many companies just started giving workers the day off.
2) Chaos and Exploitation
Not long after the phrase “Black Friday” appeared in Factory Management and Maintenance, Philadelphia law enforcement started to use the term Black Friday to refer to the floods of shoppers who descended on the city between Thanksgiving and the Army-Navy football game on Saturday.
3) Merchants Getting into the Black
“It’s a misnomer, but 20, 30 years ago, people did view Black Friday as the day that retailers started to be ‘in the black’ after a year of not being in the black,” Ray Hartjen, a retail analytics expert at RetailNext, told Vox. “All the volume through the holiday season made them profitable retailers.”
Give the whole article a look if you have the time. It's got some interesting discussion. (Oh, and Go Big Red! Beat Iowa!)