A few days ago, I looked at historical trends in seasonal name variation. It turns out Junes are more likely to be born in June than any other month and Patricks are more likely to be born on St. Patrick’s Day than any other day. I also made a slightly more puzzling discovery: The name Franklin has historically been more common on Jan. 30 than any other day:

The reason for this surfeit of Franklins? It’s not because of St. Francis’ Day—that’s traditionally celebrated in October. And Benjamin Franklin was born on Jan. 17. Franklin’s Jan. 30 surge in popularity most likely has to do with people celebrating President Franklin Delano Roosevelt, who was himself born on Jan. 30. Between 1870 and 1960, the single date with the largest proportion of babies named Franklin was Jan. 30, 1934, the first Jan. 30 during which Roosevelt was president.

Generally speaking, the popularity of Franklin is tied up with the events in Roosevelt’s political career:

Five times as many babies named Franklin were born on Election Day 1932 than were born on the preceding Tuesday and four times as many Franklins were born on Inauguration Day 1933 than were born on the preceding Saturday.

 Though Roosevelt’s approval ratings remained positive throughout most of his four terms, enthusiasm for the name Franklin dwindled. The rate of Franklin-naming during Roosevelt’s first 100 days in office was ten times higher than in his last 100 days. Every January and specifically Jan. 30 he was in office, there were smaller spikes in the name’s popularity, with the three biggest spikes occurring in 1934 and 1935 (the first two Januarys of his presidency) and in 1942 (the January following Pearl Harbor).

Franklin was not the only president to influence first names throughout the nation.   Below is a graph showing the influence of the five presidents to serve between 1913 and 1945. (Each president is highlighted from his Election Day until his last day in office.)

Each of these five names reached their peak single-day popularity at some point during their respective president’s time as commander in chief. Below is the day between 1870 and 1960 with the highest proportion of babies with each given name.

Woodrow: March 4, 1913 (Woodrow Wilson’s first Inauguration Day)
Warren: Nov. 2, 1920 (Warren Harding’s first Election Day and his birthday, too)
Calvin: Nov. 4, 1924 (Calvin Coolidge’s first Election Day)
Herbert: Nov. 6, 1928 (Herbert Hoover’s first Election Day)
Franklin: Jan. 30, 1934 (Franklin Roosevelt’s first birthday while president)

All five of these presidents had relatively obscure names that surged in popularity once they were elected or took office. It’s harder to measure the effect on naming of presidents like William McKinley and William Taft:

Compare William to an extremely uncommon name, like Grover Cleveland’s:

The difference between McKinley’s election month and the year before it is about 710 Williams per 100,000 while Grover surged 850 per 100,000 between November 1883 (the year before Cleveland’s election) and November 1884 (when he was actually elected).

What about monthly trends in more recent presidential names, like Barack or Ronald? It’s hard to say based on my data set. The Social Security Administration does not release date-specific naming data until a person is dead, making this type of analysis difficult for more recent presidents. (Babies named for such recent presidents are probably for the most part still alive, and thus not in my data set.) If you rank all 28 unique presidential first names by how often the appear in the Social Security Death Index, Rutherford and Lyndon are the second and third most rare while our current presidential first name, Barack, comes in last. (Rarer than Millard!) Meanwhile John, William, and James, the three most common first names in the Social Security Death Index, also happen to account for 14 of our 43 American presidents.