Happy Twosday: 2-22-22 marks a palindrome date hundreds of years in the making

Symbolic graphic for Twosday (Photo by XAMAX/picture alliance via Getty Images)

Palindrome fans rejoice. Tuesday marks the 22nd day of February, or 2/22/22 and many people across social media have already coined the special day as "twosday."

"Tomorrow is Tuesday 2-22-22 aka #Twosday!!! What's the significance? I haven't got a two!!" wrote icon Pee-wee Herman.

This rare calendrical event is also special because all the numbers on the date are 2 and it falls on the day of the week that actually sounds like the number.

The last time an event like this occurred was in 1622 and the next time this will happen will be in 2422.

US palindrome dates in February

Not only is Tuesday a special day but the entire week through the end of this month is filled with palindrome dates. 

  • 2-20-22
  • 2-21-22
  • 2-22-22
  • 2-23-22
  • 2-24-22
  • 2-25-22
  • 2-26-22
  • 2-27-22
  • 2-28-22

In 2021, there were 22 palindrome dates.

World palindrome dates

Once February passes, there will be no more palindrome dates in the U.S. but in other parts of the world where dates are written as date-month-year or year-month-day, there will be several palindrome dates coming their way, according to the Farmer’s Almanac:

  • 22-1-22
  • 2-2-22
  • 22-2-22
  • 22-3-22
  • 22-4-22
  • 22-5-22
  • 22-6-22
  • 22-7-22
  • 22-8-22
  • 22-9-22
  • 22-11-22

How common are palindrome dates?

Aziz S. Inan, an electrical engineering professor at the University of Portland, calculated that in the month-day-year format, palindrome days tend to occur only in the first few centuries of each millennium (1000 years). 

The last palindromic date in the second millennium (years 1001 to 2000) was Aug. 31, 1380 or 08-31-1380, according to Timeanddate.com.

The first of 36 palindrome days in the current millennium (Jan. 1, 2001 to Dec. 31, 3000) was Oct. 2, 2001 (10-02-2001) and the last will be Sept. 22, 2290 (09-22-2290), the website continued. 

Over a decade ago, the world got to celebrate two "Onesdays" with the dates 11.1.11 and 11.11.11.