The superstition surrounding Friday the 13th is a “double whammy” of two separate fears: the belief that Friday is an unlucky day and that 13 is an unlucky number. While its exact origin is murky, it is widely rooted in Western religious and cultural traditions. 

Core Superstitions and Behaviors

On this day, people often avoid specific actions to ward off perceived misfortune: 

• Dining with 13 people: Many believe having 13 guests at a table is a bad omen, with some fearing one of them will die within a year.
• Starting new projects: It is traditionally considered an unlucky day to begin a journey, get married, or start a new job.
• General “bad luck” triggers: Common superstitions like walking under a ladder, breaking a mirror (7 years of bad luck), spilling salt, and crossing paths with a black cat are often taken more seriously on this date. 

Origins of the Fear

The dread associated with this date typically stems from three major areas: 

• Christian Tradition:
  • The Last Supper: Judas Iscariot, the betrayer, was the 13th guest at the Last Supper.
  • Crucifixion: Jesus was crucified on a Friday.
  • Biblical “Firsts”: Some believe Adam and Eve ate the forbidden fruit and Cain killed Abel on a Friday the 13th.
• Norse Mythology: At a dinner in Valhalla for 12 gods, the trickster god Loki arrived uninvited as the 13th guest, leading to the death of Balder, the god of light.
• Historical Events: On Friday, October 13, 1307, King Philip IV of France ordered the mass arrest of the Knights Templar, a powerful military order, leading to their torture and execution. 

Modern Impact and Terminology

• Economic Cost: Between 17 and 21 million Americans are estimated to fear the date, causing a measurable dip in economic activity—estimated at $700 to $900 million—as people avoid flying or making major purchases.
• Psychology:
  • Triskaidekaphobia: The fear of the number 13.
  • Paraskevidekatriaphobia (or Friggatriskaidekaphobia): The specific fear of Friday the 13th.
• Buildings: Many high-rises, hotels, and hospitals omit the 13th floor or room number 13 to accommodate superstitious guests. 

Cultural Variations

Not every culture views Friday the 13th as unlucky:

• Spain and Hispanic countries: Tuesday the 13th (Martes 13) is the unlucky day.
• Italy: Friday the 17th is considered far more ominous.
• China: The number 13 is often considered lucky.