Today is the day after Thanksgiving, when holiday shopping kicks off and sales-hunters are in full frenzy. The day has come to be known in the United States as "Black Friday," and there are a number of myths about the origin of the name. Retailers would like you to believe that it's the day when stores turn a profit on the year, thus "going into the black." But don't you believe it: the true origins come from traffic-weary police officers in Philadelphia in the early 1960s.

The latest research on the origins of "Black Friday" has been conducted by Bonnie Taylor-Blake, who has shared her findings on the mailing list of the American Dialect Society. The earliest known example of "Black Friday" to refer to the day after Thanksgiving is from an article entitled "Friday After Thanksgiving" in the November 1951 issue of Factory Management and Maintenance. The article (posted by Taylor-Blake here) was about worker absenteeism on that day, rather than the shopping rush.

But in the early 1960s, "Black Friday" came to be used in Philadelphia to describe the post-Thanksgiving shopping rush. Taylor-Blake discovered an article in a public relations newsletter from 1961 that uses "Black Friday" in its current meaning:

Santa has brought Philadelphia stores a present in the form of "one of the biggest shopping weekends in recent history." At the same time, it has again been proven that there is a direct relationship between sales and public relations.

For downtown merchants throughout the nation, the biggest shopping days normally are the two following Thanksgiving Day. Resulting traffic jams are an irksome problem to the police and, in Philadelphia, it became customary for officers to refer to the post-Thanksgiving days as Black Friday and Black Saturday. Hardly a stimulus for good business, the problem was discussed by the merchants with their Deputy City Representative, Abe S. Rosen, one of the country's most experienced municipal PR executives. He recommended adoption of a positive approach which would convert Black Friday and Black Saturday to Big Friday and Big Saturday. The media cooperated in spreading the news of the beauty of Christmas-decorated downtown Philadelphia, the popularity of a "family-day outing" to the department stores during the Thanksgiving weekend, the increased parking facilities, and the use of additional police officers for guaranteeing a free flow of traffic ... Rosen reports that business over the weekend was so good that merchants are giving downtown Philadelphia "a starry-eyed new look."

—Public Relations News, Dec. 18, 1961, p. 2.

The origin of "Black Friday" among Philadelphia police officers of the early '60s is further reinforced by a 1994 article for The Philadelphia Inquirer by Joseph P. Barrett, who recounted his role in popularizing the expression when he worked as a reporter for The Philadelphia Bulletin. He credits the traffic cops, who had to work 12-hour shifts the day after Thanksgiving.

In 1959, the old Evening Bulletin assigned me to police administration, working out of City Hall. Nathan Kleger was the police reporter who covered Center City for the Bulletin.

In the early 1960s, Kleger and I put together a front-page story for Thanksgiving and we appropriated the police term "Black Friday" to describe the terrible traffic conditions.

Center City merchants complained loudly to Police Commissioner Albert N. Brown that drawing attention to traffic deterred customers from coming downtown. I was worried that maybe Kleger and I had made a mistake in using such a term, so I went to Chief Inspector Albert Trimmer to get him to verify it.

Trimmer, tongue in cheek, would say only that Black Friday was used to describe the Valentine's Day massacre of mobsters in Chicago.

The following year, Brown put out a press release describing the day as ''Big Friday." But Kleger and I held our ground, and once more said it was ''Black Friday." And of course we used it year after year.

—"This Friday Was Black with Traffic," Philadelphia Inquirer, Nov. 25, 1994

It's notable that both articles discuss how much Philadelphia merchants disliked the label "Black Friday" and tried to get people to use a more positive term: "Big Friday." That effort failed, of course, and "Black Friday" caught on, spreading to other cities in the 1970s and '80s. And instead of trying to replace "Black Friday" with "Big Friday," retailers and advertisers found a new way of ameliorating the name for the day: circulating the story that "Black Friday" is so called not because of the disastrous traffic conditions but because of the profits seen by stores.

According to Taylor-Blake, the story of businesses getting "back in the black" on Black Friday doesn't start appearing until the 1980s. So the "back in the black" explanation was clearly a way to rebrand Black Friday with more positive connotations. It's worth noting that all of the historical predecessors for the modern Black Friday were negative events. One early "Black Friday" was on Dec. 6, 1745, when news of the landing in Scotland of Charles Edward Stuart, pretender to the throne, was publicized in London. "Black Friday" was also used to describe financial panics of 1869 and 1873. Despite that history, and the experience of the poor Philadelphia traffic cops, the commercial propaganda about "Black Friday" being connected to "black ink" (profitability) has obscured the true origins of the term. As always, watch out for etymythology!

Update: Welcome, listeners of NPR's Morning Edition!