Findmypast.com researchers analyzed the records of the U.S. Social Security Administration, which has recorded baby names, based on Social Security applications for births, since 1879.

The top 10 most popular girl names in 1940, they found, have fallen by an average of over 700 places in the popularity rankings since – nearly seven times as far as the top 10 boys’ names the same year, which have dropped an average of barely 100 places.  None of the top 10 girls’ names in 1940 even make today’s top 100. Three of the top 10 names from 1940 (Betty, Carol, Shirley) have now dropped entirely from the top 1,000, compared to none of the equivalent boys’ names. Betty, Carol and Shirley are now the names of deceased grandmothers and aged aunts – the names that time forgot.

“Baby names are like period pieces”, says Josh Taylor, genealogist for findmypast.com.  “Some recall a particular era, which can make them clues when researching family history.  So, you can sometimes guess roughly when someone was born simply by their first name.
In such cases, names can be to genealogy what carbon-dating is to archaeology.”  This is far truer, however, of girls’ names than of boys’.

Most of the top 10 ten girls’ names today were rare in 1940, while at least three (Madison, Mia, Abigail) did not even rank in the top 1,000. “In 1940 you were as likely to meet a girl named Madison as a boy named Sue”, says Taylor. Seven of today’s top 10 girls’ names have risen over 500 places since 1940, compared to just four of the boys’.

Not only do the most popular girl names change more rapidly over time but girls’ names are also more varied, with the 10 most popular ones accounting for a smaller share of all girls than the equivalent figure for boys. Meanwhile, at least half of the 10 most popular boys’ names today have biblical or Hebrew origins – more than in 1940 – compared to one (or arguably two) of the girls’ names.

10 Most Popular Girl Names in 1940

10 Most Popular Boy Names in 1940

10 Most Popular Names in the U.S. in 2011