Tuesday is the first day of this century’s final 10-day stretch of palindrome dates — at least, in the United States. A palindrome is typically a word, such as the name Bob, that reads the same backward and forward. With dates, it occurs when the numerical signature of the day is symmetrical in the same way.
Because dates are formatted differently from country to country, not all dates that are palindromic in one format are palindrome days in another. In the United States, dates are generally expressed by month first, then day, then year. But many countries write the day first, then the month, then the year.
Tuesday is Sept. 10, 2019, which in the U.S. is written 9-10-19. Turn that around and look at it again: it’s 91019 either way.
That same pattern will hold true for the next 10 days:
Ten-day palindrome stretches are not that rare, according to Time and Date.
We’ve had a similar stretch every year since 2011, when it first occurred from Jan. 10 (1-10-11) to Jan. 19 (1-19-11). In 2012, the same sequence of dates occurred in February, and so on.
“As long as you write your date in the m-dd-yy format, every century has nine years with 10 palindrome days in a row. These years are always in the second decade of the century. For example, every year between 2011-2019, 2111-2119, and 2211-2219 has had or will have 10 consecutive Palindrome Days,” according to Time and Date.
While this is our last 10-day stretch of palindrome dates in the 21st century, we’ll still get an individual palindrome day on occasion. If you write dates mm-dd-yy, the next one will be Feb. 11, 2020 (02/11/20).