My friend Judy used to always say that whenever she met another Judy, she knew exactly how old that Judy was—to the day.
That level of precision might be a bit of a stretch, but, as the above map wonderfully shows, there's good reason for that line of thinking. The most popular baby girl names in the United States are flashes in the pan—each one appearing on the map briefly, before being swept out by an up-and-comer.
The map was built in Adobe Illustrator by Deadspin's Reuben Fischer-Baum using data from the Social Security Administration. "Color palette," Fischer-Baum wrote to me over email, "has to be credited to Stephen Few, from his excellent data viz book Show Me The Numbers." Earlier drafts gave each name a unique color, he says, but in the end "it was a lot cleaner and more interesting to limit the palette to just the most popular name for any given year, and put the rest in grayscale so you could see how the different 'eras' of top names progressed."
Over at Jezebel, Fischer-Baum describes the picture that emerges:
Baby naming generally follows a consistent cycle: A name springs up in some region of the U.S.—"Ashley" in the South, "Emily" in the Northeast—sweeps over the country, and falls out of favor nearly as quickly. The big exception to these baby booms and busts is "Jennifer", which absolutely dominates America for a decade-and-a-half. If you're named Jennifer and you were born between 1970 and 1984, don't worry! I'm sure you have a totally cool, unique middle name.
Behind Fischer-Baum's data visualization is another tale—a lovely one—which explains why we have this baby name data in the first place. Turns out, this GIF owes its very existence to one curious dad. As Ruth Graham wrote in The Boston Globe earlier this year:
In 1997, Michael Shackleford was an employee of the Office of the Actuary at the Social Security Administration’s headquarters in Baltimore; his wife was pregnant and he was determined to avoid giving the child a common name like his own. With his access to Social Security card data, he wrote a simple program to sort the information by year of birth, gender, and first name. Suddenly he could see every Janet born in 1960. He could see that the number one names in 1990 were Michael and Jessica. He realized this could be important. “I knew that my eyeballs were seeing this list of the most popular baby names nationwide for the first time,” he recalled recently. “It was too good to keep to myself.”
And indeed it was—especially in its GIF incarnation.
This post originally appeared on The Atlantic.