The day’s name originated in Philadelphia, where it originally was used to describe the heavy and disruptive pedestrian and vehicle traffic which would occur on the day after Thanksgiving.
Use of the term started before 1961 and began to see broader use outside Philadelphia around 1975. Later an alternative explanation was made: that retailers traditionally operated at a financial loss (“in the red”) from January through November, and “Black Friday” indicates the point at which retailers begin to turn a profit, or “in the black”.
For many years, it was common for retailers to open at 6am, but in the late 2000s many had crept to 5am or even 4am. This was taken to a new extreme in 2011, when several retailers opened at midnight for the first time. In 2012, Walmart and several other retailers announced that they would open most of their stores at 8pm on Thanksgiving prompting calls for a walkout among some workers. There have been reports of violence occurring between shoppers on Black Friday.
It is common for prospective shoppers to camp out in an effort to secure a place in front of the line and thus a better chance at getting desired items; because this poses a significant safety risk (such as the use of propane and generators in the most elaborate cases, and in general, the blocking of emergency access and fire lanes) at least one city has banned this practice.