According to Snopes.com, the term ‘Black Friday’ did not originate with the practice of selling off slaves on the day after Thanksgiving.
“Black Friday” is the (originally derisive, now mainstream) term for the phenomenon that takes place in the U.S. on the day after Thanksgiving Thursday, when millions of consumers who get the day off from work or school crowd into stores for what is traditionally considered the beginning of the Christmas shopping season. The origins of the term “Black Friday” have become somewhat obscured in the mists of time, however, leading people to invent fanciful explanations for how that phrase became attached to the day after Thanksgiving. The example reproduced above posits the term started with a tradition of slaveowners or slave traders using that day as an opportunity for selling their wares.
The use of “Black Friday” as a descriptor for the day after Thanksgiving has nothing to do with the selling of slaves, though, and the term didn’t originate until nearly a century after the practice of slavery was abolished in the U.S. The earliest known use of “Black Friday” in such a context stems from 1951 and referred to the practice of workers calling in sick on the day after Thanksgiving in order to have four consecutive days off (because that day was not yet commonly offered as a paid day off by employers):
The Snopes.com web site was founded by David Mikkelson, a project begun in 1994 as an expression of his interest in researching urban legends that has since grown into the oldest and largest fact-checking site on the Internet, one widely regarded by journalists, folklorists, and laypersons alike as one of the world’s essential resources. Snopes.com is routinely included in annual “Best of the Web” lists and has been the recipient of two Webby awards. Snopes.com personnel have made multiple appearances as guests on national news programs such as 20/20, ABC World News, CNN Sunday Morning, and NPR’s All Things Considered, and they and their work have been profiled in numerous major news publications, including The New York Times, the Los Angeles Times, The Washington Post, The Wall Street Journal, and Reader’s Digest.