It's Palindrome Week (But Not the Last One of the Century)

Palindromes are words, phrases or a sequence of numbers that can be read the same way forward and backward

A Toyota's a Toyota -- but we got it wrong in saying that this week is the last palindrome week of the century.

It's actually the last one this decade.

Palindromes are words, phrases or a sequence of numbers that can be read the same way forward and backward. Some examples: Mom! Dad! Wow! Tell a ballet.

Tuesday -- 9/10/19 -- kicked off a 10-day week when all the numbers line up using a m/dd/yy format (9/10/2019 also worked).  

Here's how it looks:


Farmers' Almanac noted that using the same format each century gets nine years with 10 consecutive palindrome days, and they always happen in the second decade of that 100-year span.  

But that doesn't mean those are the only palindrome weeks we can expect over a lifetime, as some readers pointed out when we cited incorrect information on Tuesday. There's another 10-day palindrome week that kicks off on 1/20/21, for example. More 10-day series start on 3/20/23, 4/20/24, 5/20/25 and so on through 9/20/29. 

We can expect lots of other palindrome days ahead on the calendar in various combinations of digits. NBC News first reported back in 2011 about a professor at University of Portland, Aziz Inan, who has studied numerical palindromes. He compiled a list here of 38 "full palindrome dates" for the 21st Century (in a month/day/year format that uses four numbers for the year). The next one up is Feb. 2, 2020 (02/02/2020).

Inan says that 02/02/2020 is extra special because the 8-digit palindrome date also works for countries that use the day/month/year format. 

"No matter where they are, all the people on this planet will celebrate this palindrome on the same calendar date," Inan wrote in an email. He calls that rare palindrome a "ubiquitous palindrome date" and hopes that it can become known as a "peace day." 

The word palindrome comes from the Greek palindromos and signifies a running back again, according to The ancient Greeks famously inscribed a palindrome phrase on fountains.

For those who want to know when to expect more palindrome weeks (using two-digit year numbers), here's Inan's list through 2045 and another list through 2100. Happy hunting. 

And here's a good list of palindrome words and phrases.

CORRECTION (Sept. 11, 2019, 8:46 a.m. ET): This story was updated after an earlier version misstated the frequency of palindrome weeks.

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