To prepare for Thanksgiving, maybe you've been collecting recipes, foraging for the best sweet potatoes in the grocery store, or dusting off your nicest wine glasses. Or maybe, instead, you've been clipping coupons and scouring the internet for deals in preparation for what comes after: Black Friday.

Harvard Business School historian Nancy Koehn joined Boston Public Radio to discuss how this national day of shopping became as integral to the holiday weekend as Turkey Day itself.

"For years and years, people colloquially talked about it as being 'Black Friday' because it was the day in the year retailers could start running 'in the black' after running 'in the red,' because so many of their sales are generated during the holiday period," Koehn explained.

But the term may really have originated in the 1950s from the Philadelphia Police Department.

"The most likely antecedent is people would pour into Philadelphia from the suburbs and all around [and] create parking havoc — not quite the mob behavior and civil unrest that is part of some Black Friday experiences, but made the cops' lives a living hell," Koehn continued. "They started talking about the day as 'Black Friday.'" 

Harvard historian Nancy Koehn holds the James E. Robison Chair of Business Administration at Harvard Business School. To hear her full interview with Boston Public Radio, click on the audio player above.