1.) The fear of the number 13 has been given a scientific name: “triskaidekaphobia“; and on analogy to this the fear of Friday the 13th is called paraskevidekatriaphobia, from the Greek words Paraskeví (Παρασκευή, meaning “Friday”), and dekatreís (δεκατρείς, meaning “thirteen”).

2.) According to the Stress Management and Phobia Institute in Asheville, N.C., an estimated 17 to 21 million people in the U.S. are affected by a fear of this day, making it the most feared day and date in history.

3.) It has been estimated that $800 or $900 million is lost in business on this day, due to people’s fears of doing business, taking flights or even getting out of bed!

4.)A study in the British Medical Journal, published in 1993, concluded that there is “a significant level of traffic-related incidences in the UK on Friday the 13th, as opposed to any other random Friday.

5.) The origin of fears surrounding Friday the 13th is unclear. There is reportedly no written evidence of Friday the 13th superstition before the 19th century, but superstitions surrounding he number 13 date back to at least 1700 BC.

6.) The number 13 has been considered cursed around the world for thousands of years. The number 12 is historically considered the number of completeness, while 13 is an outlier.

7.) The number 13 is so disliked that many cities do not have a 13th Street or a 13th Avenue; many high rise buildings avoid having a 13th floor and some hospitals avoid labeling rooms with the number 13. Many airports will not have a gate 13.

8.) Popularity of the superstition may have come from the publication of Thomas W. Lawson’s popular novel, Friday the Thirteenth. In the novel, a stock broker takes advantage of the superstition to create a Wall Street panic on Friday the 13th.

9.) Speaking of the stock market, in Oct. 1989, Wall Street saw, what was at the time, the second largest drop of the Down Jones Industrial Average in history. The day was nicknamed the Friday-the-13th mini crash.

10.) Some historians believe that superstitions surrounding this day date back to Biblical times. Some claim that it was the day on which Eve bit the apple from the Tree of Knowledge.

11.) Some Friday the 13th superstitions that are believed to cause bad luck include walking under a ladder, having a black cat cross your path, or breaking a mirror.

12.) Crossing your fingers, a rabbit’s foot, making a wish on a wishbone or knocking on wood are believed to ward off evil or bad luck during Friday the 13th.

13.) Mary Kate and Ashley Olson, Julia Louis-Dreyfus, and Steve Buscemi (who incidentally is the voice behind the self-guided walking audio tours at The Eastern State Penitentiary in Fairmount) were all born on a Friday the 13th.