The phrase, in fact, was coined in the 1960s and is believed to have started in Philadelphia, where it was used to describe the heavy and disruptive pedestrian and vehicle traffic that would occur the day after Thanksgiving. This year, the National Retail Federation expects that 138 million shoppers will hit the mall on Nov. 26, up 4% from its forecast in 2009. >>Black Friday Center Of course, forecasts for spending on Black Friday vary by research firm, but ShopperTrak said the day after Thanksgiving will once again be the biggest sales day of the holiday season. Black Friday and the Saturday before Christmas often finish neck-and-neck in the race for the highest volume sales days. Still, while Black Friday continues to be important, retailers have begun to take a different approach, looking to pick up shoppers' dollars ahead of Thanksgiving weekend. Wal-Mart ( WMT), Target ( TGT), Sears ( SHLD), Kohl's ( KSS), J.C. Penney ( JCP) and Best Buy ( BBY) started promoting the holiday season in early November with pre-Black Friday discounts. This, coupled with shoppers' propensity toward procrastination as seen during the back-to-school season, could lead sales to be spread out even more during the holiday season. --Written by Jeanine Poggi in New York. >To contact the writer of this article, click here: Jeanine Poggi. >To follow the writer on Twitter, go to http://twitter.com/jpoggi. >To submit a news tip, send an email to: email@example.com.