First Palindromic Memorial Day
By Aziz Inan
Memorial Day, observed annually on the last Monday of May, is a day to honor and remember the men and women who died while serving in the U.S. Armed Forces. Because the date varies each year, Memorial Day can fall anywhere between May 25 and May 31.
Memorial Day officially became a U.S. national holiday in 1971, following the enactment of the Uniform Monday Holiday Act in 1968. Prior to that, Memorial Day—then known as Decoration Day—was traditionally observed on May 30, regardless of the weekday.
This year, Memorial Day falls on Monday, May 26, 2025, and it has a rare and fascinating feature: when written in the short format as 5/26/25, it forms a palindrome—a sequence that reads the same forwards and backwards.
Interestingly, 2025 contains 11 palindromic dates, all occurring in May. This is because the year ends in “25” and May is the fifth month, allowing for symmetry in the date format. The first palindromic date this year was 5/2/25. The remaining ten are a consecutive string from May 20 through May 29:
5/20/25, 5/21/25, 5/22/25, 5/23/25, 5/24/25, 5/25/25, 5/26/25, 5/27/25, 5/28/25, and 5/29/25.
Among them, 5/20/25 is particularly notable because it is also a full seven-digit palindrome when written as 5/20/2025.
So, Memorial Day this year, May 26, 2025, will be the first palindromic Memorial Day in U.S. history—a truly rare occurrence. In fact, there are no other palindromic Memorial Days in this century.
However, the 22nd century will feature two palindromic Memorial Days:
- May 28, 2125 (5/28/25)
- May 30, 2135 (5/30/35)
For a date to qualify as a palindromic Memorial Day, the year must end in 25 (when Memorial Day falls between May 25 and 29) or 35 (when Memorial Day falls on May 30 or 31).
By contrast, the 23rd century will have none, as neither Memorial Day May 30, 2225, expressed as 5/30/25 nor Memorial Day, May 25, 2235, expressed as 5/25/35 are palindromic in form.
In summary, each century may contain one, two, or no palindromic Memorial Days, making this year’s occurrence exceptionally rare.
So take a moment to appreciate—and perhaps share—the uniqueness of this upcoming Monday, May 26, 2025, a once-in-a-lifetime palindromic Memorial Day.
P.S. The only palindromic Decoration Day occurred on May 30, 1935—written as 5/30/35.
(Inan is a professor of electrical engineering at the Donald P. Shiley School of Engineering at the University of Portland.)
