This year will mark my seventh birthday.
You may find that statement confusing, given that I’m an adult woman. But nevertheless I’ll be turning 28 years old on Feb. 29—a leap day.
To make sense of my baffling predicament, you first need to understand what leap days are and why leap years exist in the first place.
The way we measure time on Earth is a bit complicated. For example, we measure years by the length of time it takes our planet to orbit the sun. We call this a “solar” or “tropical” year. But while most of us understand a year as comprising 365 days, that’s not exactly right. The precise measure of a solar year is 365.24219 days.
That might seem like an insignificant difference. But those numbers at the end of the decimal point add up. Without any sort of adjustment for the extra quarter of a day, seasons as we know them would eventually become very different. Winter would feel like summer, and we’d have Christmas in July.
In 46 BCE, Roman dictator Julius Caesar sought to fix this problem. He introduced the Julian calendar—an amended version of the existing Roman calendar. A year, he said, would now include 365 days, with an extra leap day—or intercalary day—every fourth year.
While this solution was inventive, it wasn’t quite right, according to physicist Judah Levine, a man the Washington Post once dubbed “the nation’s timekeeper.”
“It’s not exactly a quarter of an extra day; it’s a little less,” Levine, who works in the time and frequency division of the National Institute of Standards and Technology in Boulder, Colorado, tells Quartz. “And so adding one day every four years was too much.”
That miscalculation resulted in a surplus of 11 minutes each year. By the 1500s, the Julian calendar and the solar year were misaligned by about 10 days. So in 1582, Pope Gregory XIII established the Gregorian calendar and introduced the century rule, Levine explains.
“If a leap year falls on a century, a year ending in double zeroes, you only add a leap day if it’s divisible by 400,” he says. “For that reason 1900 wasn’t a leap year but 2000 was.”
In 2100, we’ll skip it again, forcing leap babies to wait a total of eight years to celebrate their birthday.
Within the US, there are two notable communities that encourage leap babies to come together and celebrate. One is the Leap Year Birthday Celebration in the town of Anthony, which straddles the border between Texas and New Mexico. This year, that celebration will include a wine tasting, cowboy re-enactments, and a parade.
Anthony was declared the Leap Year Capital of the World in 1988 after Mary Ann Brown, a resident who was born Feb. 29, 1932, petitioned the governors of Texas and New Mexico to make the title official.
“It’s a special privilege,” Benjamin Romero, mayor pro-tem of Anthony, Texas, tells Quartz. “This year we have leap day babies coming from as far as Australia, India, and England.”
The other outlet is the Honor Society of Leap Year Day Babies, where fellow leapers can get together online and commiserate. The National Center for Health Statistics tracks birth rates, but they don’t keep statistics on the number of babies born on specific days. Raenell Dawn, co-founder of Honor Society of Leap Year Day Babies, and her co-founder Peter Brouwer—both leapers themselves—estimate that the odds of bearing this distinctive honor is around one in 1,461.
“It’s about 684 in a million,” Dawn says. “There are about 200,000 in the United States and just under 5 million worldwide.”
This means that while my fellow leap babies and I are a small enough group to maintain a feeling of exclusivity, we’re also large enough to spark a healthy community dialogue. And once we get to talking, it’s evident that many of our individual struggles are really quite universal. One of the topics frequently discussed is which day leap babies should use to celebrate their birthday on off-years.
According to Dawn, “it’s close to 50-50.”
Some opt for Feb. 28, saying the last day of February is most accurate, while others insist March 1 is more correct because they were born the day following Feb. 28. Then there’s the camp that believes time of day is the determining factor—if you were born in the morning, the 28th is yours, but if you were delivered past noon, it’s the 1st. It can all get rather heated.
But by far the most popular topic of conversation among leaplings is the bureaucratic problems we all inevitably face. This red-tape nightmare can take many forms. Sometimes it’s as small as not being able to select our birth date from a drop-down menu online—or those several years when Facebook didn’t acknowledge we had a birthday. Often it’s more substantial, like dealing with inaccurate legal documents.
And all modern leap babies have to navigate these snafus for two milestones. Both our 18th and 21st birthdays fall on off-years, and US states have historically struggled to figure out a workable solution. When I was younger, my driver’s license in Florida listed my real birthday, but it also read “under 21 until 2/29/2009,” a date that didn’t actually exist. As for my 18th, well, it was up to individual businesses to determine whether they considered me legal on Feb. 28 or March 1. Results varied.
Dawn says this is all too common, and there’s no standard for how Feb. 29 birthdays are handled. It differs from state to state, and case to case.
“There’s one leapling I talked to whose birthday certificate says February 28 and her license says March 1,” Dawn said. “February 29 isn’t listed on either document.”
But despite the occasional headache, I think all leap babies derive a certain pride from their semi-unique status. Many people say it makes them feel special, not to mention enabling them to go all out celebrating those rare “real” birthdays. Leap babies are also fond of claiming that we’re inherently young at heart.
My mom always offered me the same consolation, telling me that I’d thank her one day–on the morning when I can truthfully tell the world I’m only 10 instead of 40.