13 Things to Know About Friday the 13th

3 minute read

Don’t step on any sidewalk cracks, walk under any mirrors, or encounter any black cats, because it’s Friday the 13th, the unluckiest day of the year. Here are 13 things to know about why the day is considered so ominous.

1. Some superstitions about Friday the 13th are rooted in the guest list of the Last Supper. Judas was the 13th guest at the table, and Jesus was crucified on a Friday. Coincidence?

2. On Friday the 13th in 1307, thousands of Knights Templar were arrested on orders from King Philip IV of France because of suspicions that their secret initiation rituals made them “enemies of the faith.” After years of torture, they were burned at the stake. Dan Brown’s novel The DaVinci Code popularized the link between the Knights Templar and Friday the 13th.

3. Friday was considered an unlucky day as early as the 14th century. Geoffrey Chaucer wrote in The Canterbury Tales that “on a Friday fell all this mischance.”

4. The first specific written reference to Friday the 13th as an unlucky day was in an early-20th century novel by Thomas W. Lawson, called Friday, the 13th. Ironically, a ship named after Lawson was caught in a storm and shipwrecked on the night of Friday the 13th, 1907.

5. Not all cultures believe Friday the 13th is unlucky. In Greek and Hispanic cultures, Tuesday the 13th is considered far more ominous. In Italy, Friday the 17th is spookier than the 13th.

6. The bad luck on Friday the 13th may be a self-fulfilling prophecy. One 1993 study found that hospital admissions for traffic accidents were 52% higher on Friday the 13th than Friday the 6th.

7. But it also might be hogwash: A German study found no spike in hospital admissions or procedures on Friday the 13th.

8. Superstition can result in an economic dip. Donald Dossey, founder of the Stress Management Center and Phobia Institute, says U.S. businesses lose millions of dollars on Friday the 13th, because some people are reluctant to leave their homes.

9. Any month that starts with a Sunday will contain a Friday the 13th, and there can be as many as three of them a year; 2015 will have two more Fridays like this one.

10. Mary Kate and Ashley Olson, Julia Louis-Dreyfus, and Steve Buscemi were all born on Friday the 13th.

Friday the 13th With the Anti-Superstition Society of Chicago

Cookies at the 13th Anniversary Jinx-Jabbing Jamboree and Dinner of the Anti-Superstition Society of Chicago, 1940.
Cookies at the 13th Anniversary Jinx-Jabbing Jamboree and Dinner of the Anti-Superstition Society of Chicago, 1940.William C. Shrout—The LIFE Picture Collection/Getty Images
Friday the 13th Jinx-Jabbing Jamboree and Dinner of the Anti-Superstition Society of Chicago, December 1940
Caption from LIFE. Panther, a three-year-old black cat, is delivered to General Lorenzen, Keeper of Black Cats, by its mistress, Mrs. Olive Morrison. The Society advertised in the paper for a 'large, docile black cat' to preside at meeting, got 159 offers.William C. Shrout—The LIFE Picture Collection/Getty Images
Anti-Superstition Society of Chicago
Caption from LIFE. Going home, members walk under a ladder, topped by umbrella. Thoroughly immunized against bad luck, all got home safely, woke up next day without hangovers.William C. Shrout—The LIFE Picture Collection/Getty Images
Strange scene at the 13th Anniversary Jinx-Jabbing Jamboree and Dinner of the Anti-Superstition Society of Chicago, December 1940.
Strange scene at the 13th Anniversary Jinx-Jabbing Jamboree and Dinner of the Anti-Superstition Society of Chicago, December 1940.William C. Shrout—The LIFE Picture Collection/Getty Images
Busting a mirror, club president Nathaniel Leverone calls meeting to order. Guests all stood, grabbed horseshoes, gave a concerted razzberry to 'Old Man Superstition.'
Caption from LIFE. Busting a mirror, club president Nathaniel Leverone calls meeting to order. Guests all stood, grabbed horseshoes, gave a concerted razzberry to 'Old Man Superstition.'William C. Shrout—The LIFE Picture Collection/Getty Images
Crossing cutlery presages bloodshed, according to old superstition. Unafraid are: Champ Carey, vice president of Pullman Co.; Paddy Driscoll, ex-coach of Marquette football team; Fred Gillies, superintendent of Inland Steel Co.
Caption from LIFE. Crossing cutlery presages bloodshed, according to old superstition. Unafraid are: Champ Carey, vice president of Pullman Co.; Paddy Driscoll, ex-coach of Marquette football team; Fred Gillies, superintendent of Inland Steel Co.William C. Shrout—The LIFE Picture Collection/Getty Images
Occupational groups sat at 13 different tables, marked by these cards. Aviation men were camera shy because of Chicago airplane crash which occurred week before party.
Caption from LIFE. Occupational groups sat at 13 different tables, marked by these cards. Aviation men were camera shy because of Chicago airplane crash which occurred week before party.William C. Shrout—The LIFE Picture Collection/Getty Images
Three on a match are James O'Keefe, Chicago City Sealer; Nathaniel Leverone; General A. F. Lorenzen, U.S.A., retired. Match superstition started during Boer War when night snipers picked off British soldiers as they lighted up.
Caption from LIFE. Three on a match are James O'Keefe, Chicago City Sealer; Nathaniel Leverone; General A. F. Lorenzen, U.S.A., retired. Match superstition started during Boer War when night snipers picked off British soldiers as they lighted up.William C. Shrout—The LIFE Picture Collection/Getty Images
Cached in coffin, new member is inducted into club. Initiate: Thomas J. Callaghan, head of Chicago district of U.S. Secret Service. Horseshoe waver: General Lorenzen.
Caption from LIFE. Cached in coffin, new member is inducted into club. Initiate: Thomas J. Callaghan, head of Chicago district of U.S. Secret Service. Horseshoe waver: General Lorenzen.William C. Shrout—The LIFE Picture Collection/Getty Images
Shaking hands across the table is not only bad luck, it's unsanitary. Custom of shaking hands, now simple etiquette, was performed in ancient times as a bit of magical hocus-pocus. Bankers and brokers here express their scorn of magic and microbes.
Caption from LIFE. Shaking hands across the table is not only bad luck, it's unsanitary. Custom of shaking hands, now simple etiquette, was performed in ancient times as a bit of magical hocus-pocus. Bankers and brokers here express their scorn of magic and microbes.William C. Shrout—The LIFE Picture Collection/Getty Images
Spilling salt supposedly foreshadows a fight. Here Hugh W. Cross, lieutenant-governor-elect of Illinois, spills salt (on his shrimps) to the great amusement of Chester R. Davis and Park Livingston, trustees of the University of Illinois.
Caption from LIFE. Spilling salt supposedly foreshadows a fight. Here Hugh W. Cross, lieutenant-governor-elect of Illinois, spills salt (on his shrimps) to the great amusement of Chester R. Davis and Park Livingston, trustees of the University of Illinois.William C. Shrout—The LIFE Picture Collection/Getty Images
The Anti-Superstition Society of Chicago's mascot for its 13th Anniversary Jinx-Jabbing Jamboree and Dinner, December 1940.
The Anti-Superstition Society of Chicago's mascot for its 13th Anniversary Jinx-Jabbing Jamboree and Dinner, December 1940.William C. Shrout—The LIFE Picture Collection/Getty Images

11. There are two tough-to-pronounce names for the fear of Friday the 13th: “paraskevidekatriaphobia,” and “friggatriskaidekaphobia.

12. Twenty-five percent of Americans said they were “very” or “somewhat” superstitious in a 1996 Gallup poll, and 9% said they were wary of the number 13. Interestingly, young people were more likely to be superstitious than older people.

13. But Taylor Swift isn’t one of them. The pop star turned 13 on Friday the 13th, which is one of many reasons she says 13 is her lucky number.

Read next: 5 Actually Good Things That Happened on Friday the 13th

PHOTOS: See Taylor Swift Over the Years

2006 CMT Music Awards - Arrivals
Taylor Swift arrives at the 2006 CMT Music Awards at the Curb Event Center at Belmont University in Nashville, Tennessee.John Shearer—WireImage/Getty Images
2007 CMT Music Awards - Red Carpet
Taylor Swift arrives at the 2007 CMT Music Awards.Kevin Mazur—WireImage/Getty Images
42nd Annual Academy Of Country Music Awards - Show
Taylor Swift performs during the 42nd Annual Academy Of Country Music Awards held at the MGM Grand Garden Arena in Las Vegas, Nevada in 2007.Ethan Miller—Getty Images
2008 ACM New Artists Party For A Cause
Taylor Swift performs during the Academy of Country Music New Artists' Party for a Cause show at the MGM Grand Hotel/Casino in Las Vegas, Nevada in 2008.Ethan Miller—Getty Images
Taylor Swift and Michelle Williams Visit MTV's "TRL" - June 16, 2008
Taylor Swift performs live on MTV's "TRL" at the MTV Studios in Times Square in New York City in 2008.Gary Gershoff—WireImage/Getty Images
The 42nd Annual CMA Awards - Arrivals
Taylor Swift attends the 42nd Annual CMA Awards at the Sommet Center in Nashville, Tennessee in 2008.Ed Rode—WireImage/Getty Images
CNN Heroes "An All-Star Tribute" 2008
Singer Taylor Swift arrives at CNN Heroes: An All-Star Tribute at the Kodak Theatre in Hollywood, California in 2008.Jon Kopaloff—FilmMagic/Getty Images
Saturday Night Live
Taylor Swift performs on Saturday Night Live in 2009.NBC/Getty Images
The Brit Awards 2009 - Arrivals
Taylor Swift arrives at the Brit Awards 2009 at Earls Court in London, England.Gareth Cattermole—Getty Images
44th Annual Academy Of Country Music Awards All-Star Jam
Taylor Swift performs during the 44th annual Academy of Country Music Awards All-Star Jam at the MGM Grand Hotel/Casino in Las Vegas, Nevada in 2009.Ethan Miller—Getty Images
Taylor Swift in Concert
Taylor Swift performs at Madison Square Garden in New York City in 2009.Theo Wargo—WireImage/Getty Images
2009 MTV Video Music Awards - Arrivals
Taylor Swift arrives to the 2009 MTV Video Music Awards at Radio City Music Hall in New York City. Stephen Lovekin—FilmMagic/Getty Images
The 43rd Annual CMA Awards - Show
Taylor Swift performs at the 43rd Annual CMA Awards from the Sommet Center in Nashville, Tennessee in 2009.Katherine Bomboy—Getty Images
The 52nd Annual GRAMMY Awards - Show
Taylor Swift performs onstage at the 52nd Annual Grammy Awards held at Staples Center in Los Angeles, California in 2010.Michael Caulfield—WireImage/Getty Images
Taylor Swift drops one of her awards dur
Taylor Swift drops one of her awards during the 52nd annual Grammy Awards in Los Angeles, California in 2010.Valerie Macon—AFP/Getty Images
Taylor Swift 13 hours on the 13th. & some songs
Taylor Swift performs at the CMA Music Festival in Nashville, Tennessee in 2010.Rick Diamond—Getty Images
Grand Ole Opry 85th Birthday Bash
Taylor Swift performs during the Grand Ole Opry 85th birthday bash at the Grand Ole Opry House in Nashville, Tennessee in 2010.Tony R. Phipps—Getty Images
44th Annual CMA Awards - Show
Taylor Swift performs "Back to December" at the 44th Annual CMA Awards at the Bridgestone Arena in Nashville, Tennessee in 2010.Rick Diamond—Getty Images
taylor Swift attends the 'Alexander McQu
Taylor Swift attends the 'Alexander McQueen: Savage Beauty' Costume Institute Gala at The Metropolitan Museum of Art in 2011.TIMOTHY A. CLARY—AFP/Getty Images
2012 MTV Video Music Awards - Show
Taylor Swift performs at the 2012 MTV Video Music Awards at Staples Center in Los Angeles, California.Jason LaVeris—FilmMagic/Getty Images
BBC Radio 1 Teen Awards - Show
Taylor Swift performs at the Radio One Teen Awards at Wembley Arena in London, England in 2012.Mike Marsland—WireImage/Getty Images
BBC Radio 1 Teen Awards - Show
Taylor Swift performs at the Radio One Teen Awards at Wembley Arena in London, England in 2012.Mike Marsland—WireImage/Getty Images
Taylor Swift Switches On Westfield London Christmas Lights
Taylor Swift switches on the Christmas lights and performs for fans and shoppers at Westfield London in London, England in 2012.Mike Marsland—WireImage/Getty Images
26th Annual ARIA Awards 2012 - Arrivals
Taylor Swift arrives at the 26th Annual ARIA Awards 2012 at the Sydney Entertainment Centre in Sydney, Australia. Don Arnold—WireImage/Getty Images
26th Annual ARIA Awards 2012 - Show
Taylor Swift performs on stage during the 26th Annual ARIA Awards 2012 at the Sydney Entertainment Centre in Sydney, Australia.Brendon Thorne—Getty Images
KIIS FM's Jingle Ball 2012 - Night 1 - Show
Taylor Swift performs during night 1 of the 2012 KIIS FM Jingle Ball at Nokia Theatre LA Live in Los Angeles, California.C Flanigan—FilmMagic/Getty Images
Taylor Swift At Gillette Stadium
Taylor Swift in concert at Gillette Stadium in Foxborough, Massachusetts in 2013.Barry Chin—Boston Globe/Getty Images
2013 Victoria's Secret Fashion Show - Show
Taylor Swift performs while Candice Swanepoel walks the runway at the 2013 Victoria's Secret Fashion Show at the Lexington Avenue Armory in New York City.Jamie McCarthy—Getty Images
Taylor Swift Lives In Shanghai
Taylor Swift performs at the Mercedes-Benz Arena on May 30, 2014 in Shanghai, China.ChinaFotoPress/Getty Images
2014 American Music Awards - Show
Taylor Swift performs onstage during the 2014 American Music Awards held at Nokia Theatre L.A. Live on Nov. 23, 2014 in Los Angeles, Ca.Michael Tran—FilmMagic/Getty Images
2014 American Music Awards - Roaming Show
Taylor Swift performs at the 2014 American Music Awards at Nokia Theatre L.A. Live on Nov. 23, 2014 in Los Angeles, Ca.Christopher Polk—Getty Images
The Voice - Season 7
Taylor Swift performs on The Voice in 2014.NBC/Getty Images
2014 Victoria's Secret Fashion Show - Show
Taylor Swift performs during the 2014 Victoria's Secret Fashion Show at Earl's Court exhibition centre on Dec. 2, 2014 in London, England.Dimitrios Kambouris—Getty Images for Victoria's Secr
KIIS FM's Jingle Ball 2014  Powered by LINE  - Show
Taylor Swift performs onstage during KIIS FM's Jingle Ball 2014 at Staples Center on December 5, 2014 in Los Angeles, Ca.Christopher Polk—Getty Images

Listen to the most important stories of the day.

More Must-Reads From TIME

Write to Charlotte Alter at charlotte.alter@time.com