By John Tozzi, Bloomberg Businessweek

A century ago “Black Friday” referred to the market crash of Sept. 24, 1869, which was caused by two financiers’ failed attempt to corner the gold market. Today we know Black Friday as the country’s busiest shopping day, falling right after Thanksgiving. How did that happen?

One popular but false explanation is that the name marks the day retailers end an 11-month stretch of red ink and harvest profits for the first time all year. Others say it refers to the dark day thousands of retail workers will spend greeting shoppers, stocking shelves, folding garments and ringing registers.

In fact, factory owners in the 1950s coined Black Friday to lament the high number of workers who didn’t show up for work, as linguist Ben Zimmer pointed out last year. The connection between Black Friday, crowds and shopping came in the early 1960s from some Philadelphia cops, he explained. They used the phrase to describe the mad traffic downtown on the day holiday shoppers converged with football fans arriving for the Army-Navy game, traditionally played in Philly on the Saturday after Thanksgiving.

The name Black Friday, picked up by the press, presented a branding problem from the start. Zimmer quotes a 1961 story from Public Relations News that called the label “hardly a stimulus for good business,” and notes city spinmeister Abe Rosen’s efforts to replace it with the anodyne “Big Friday.” The Philadelphia newspapers refused, and Black Friday stuck.

It’s not exactly clear when, in the decades since, retailers across the country embraced the name. By the time they did, it came with the reassuring myth that Black Friday was the day they turned a profit to be “in the black.” (A quick look at retailers’ quarterly earnings should put that canard to rest.) The retail industry shed any queasiness it had about the Black Friday brand in recent years, as big-box stores and shopping malls embraced “doorbuster” sales that got shoppers to line up for discounts before opening time.

Although Black Friday has long been called the busiest shopping day of the year, that’s only become true in the past decade, according to data from retail analyst ShopperTrak. Before 2004, holiday shopping generally peaked on the Saturday before Christmas, the International Council of Shopping Centers reported. But after enough years of retailers and reporters and shoppers repeating that Black Friday was the busiest day, the myth eventually became true.

More recently, the hoopla has spread throughout the week. Cyber Monday was invented in 2005 by the National Retail Federation’s digital division in an attempt to promote online shopping when office workers get back to their desks after the holiday; it was not the highest-volume day for e-commerce sales. In 2010, American Express made up Small Business Saturday, with promotions and rebates aimed at getting gift seekers to swipe their AmEx cards at local merchants’ shops. Note to retailers: Three days of Thanksgiving week remain unbranded. Or four, if Thanksgiving itself is not off limits.

And, of course, it’s not. Black Friday has been creeping earlier, from dawn to midnight to Thursday evening. Walmart opened its doors on Thanksgiving Day at 8pm this year, two hours earlier than last year. Perhaps the earlier hour is an attempt to avoid the sometimes unruly crowds that door-buster sales attract. Last year, a Walmart shopper in Southern California reportedly pepper-sprayed fellow customers to reach coveted merchandise. But even that’s not Black Friday’s darkest moment: In 2008, Jdimytai Damour, a 34-year-old Queens man who took a seasonal job at a Walmart in Valley Stream, N.Y, was killed when a predawn Black Friday mob broke the glass doors and trampled him to death.

Long before such deadly excess, some activists seized the symbolism of Black Friday to make people think twice about consumer culture. Since the 1990s, the day after Thanksgiving has also been dubbed Buy Nothing Day, an idea championed by Adbusters magazine and, lately, the Occupy movement. The thought of getting masses of consumers to stay home on what has become the biggest shopping day of the year may sound like a pipe dream. But Black Friday only holds its current place in our culture through miracles of marketing, spin and rebranding. Those celebrating Buy Nothing Day, at least, don’t have to explain the name.