Friday the 13th is a dreaded day for many superstitious people, and 2015 may be one of the unluckiest years in recent memory.

Friday The 13th Superstitions

Today is Friday, March 13 and the topic of Friday the 13th is already trending on Twitter. The undesired day is considered to be a bad one by many in America, to the point that it actually has social effects on the country as a whole.

Here are five things you may not know that make Friday the 13th such a dreaded day:

1. Friday the 13th may have originated from the story of Jesus Christ

Scholars believe that the fear of Friday the 13th began with the story of Jesus' crucifixion. As detailed in the Bible, there were 13 people at the Last Supper (which was on a Thursday) and then Jesus was crucified the very next day on Friday. The story surrounding this may have been the cause of superstitions regarding the day.

2. Up to 21 million Americans suffer from a Friday the 13th phobia

Known as paraskevidekatriaphobia, a fear of Friday the 13th is instilled in 17-21 million people living in America, according to Donald Dossey, the founder of the Stress Management Center and Phobia Institute. This results in people being afraid to leave the house, rely on air travel or even get out of bed at all on Friday the 13th. As a result, between $800-900 million is lost in business on the day.

3. The 13th of the month is more likely to fall on Friday than any other day

According to the Gregorian calendar, Friday the 13th is actually more likely to occur than Tuesday the 13th or any other day of the week. Over the course of 4,800 months, Friday the 13th has happened 688 times, with Sundays and Wednesdays being closest at 687.

4. This is the second Friday the 13th in a row

Friday, March 13, 2015 marks the second straight month of Friday the 13th. February also had a Friday the 13th. Those going through a particularly bad time in their life right now may just assign blame to this unfortunate occurrence.

5. There's still another Friday the 13th coming up in 2015

November will also have a Friday the 13th, making it the third one for 2015. This is as high as it can go for a given year, last occurring in 2009. Any common year that starts on a Thursday will feature three Friday the 13ths.

While these are all troubling statistics to some, many others will simply go about their days as usual. Some may not even know it's Friday the 13th at all. To others, however, it is a day to be avoided at all costs.