By Matthew Woods, liquidsymbol.com

　　Some names become popular for a few years, and then fade out of use. Other names remain common for decades at a time. There are names you will find across the U.S., and names that only become popular in part of the country.

　　It’s difficult to pin down all of the factors parents consider when deciding what to name their baby. There’s the family history, how the name fits with the last name, whether or not the name has already been used by friends and family, and the impact of people we have known with that name. The sound and the meaning both matter. A name is something a person carries with them throughout their life, after all, and its choice is an intimate reflection of who the parents are, and what they want for their child. But despite the personal nature of the naming process, or maybe even because of it, the popularity of a name depends strongly on where and when the child was born. There is a common pattern to the way names rise and fall in popularity: the trends change smoothly over time and move in waves across the country. But there are times when events have a sudden and dramatic impact on a name’s popularity. Celebrities, spokespeople, public figures and fictional characters can raise a name to national awareness and cause sudden flashes of popularity or abrupt drops in a name’s frequency. It isn’t possible to be certain about what caused a particular change just by looking at the census data, but there are some interesting cases where national attention to a particular person coincides with a jump in the popularity of that person’s first name.

　　Princess Diana was married to Prince Charles in 1981, and died in 1997. During both of those years, the number of girls born in the U.S. with the name Diana increased sharply.

　　The name Jared was gaining momentum in the 1990s, but after 2000 it dropped abruptly. That was the same year as the launch of an advertising campaign for a certain sandwich chain featuring a spokesperson by that name.

　　In 2008 the name Madelyn had a sudden wave of popularity. During that year Barak Obama’s presidential campaign was covered extensively in the American media. Madelyn Dunham, president Obama’s grandmother, was frequently mentioned for her influential role in the presidential candidate’s upbringing, and her untimely passing two days before her grandson was elected president.

　　Of the names Shawn, Shaun, and Sean, the least common spelling has historically been Shaun. But in 1978, Shaun saw a burst of popularity that coincides with actor and singer Shaun Cassidy‘s peak popularity in the U.S. During that year he both starred in a popular television series and produced a number one hit single. It’s doubtful that all of the Shauns born in that year were named after Cassidy, but his popularity probably would have contributed to people’s familiarity with that spelling of the name.

　　Here’s a way of looking at how the most popular baby names in the U.S. have changed over the years. This video shows the individual names moving up and down as their rank in the list of top ten boy’s and girl’s names changes.

　　For other videos in this series, including the changing lists for each state and time-lapse maps of the popularity of specific names, visit liquidsymbol.com

　　Matt is an applied mathematician who lives in the Boston area. He holds bachelor’s degrees in Physics and Mathematics, and a PhD in Cognitive and Neural Systems. He became interested in baby names in 2012 after discovering, much to his surprise, that the name his wife and he had just given their new daughter turned out to be the most popular girl’s name in the country.