Republican Elise Stefanik, as our Jaime Fuller reported Monday, will almost certainly become the youngest woman ever elected to Congress after voters in the 21st district of New York head to the polls Tuesday. When I read that piece, I wondered if Stefanik was the first member of the generation known as Millennials to make it to Capitol Hill.

In fact, she's not. She will, according to analysis of data from GovTrack.us, be the fourth member of the Millennial generation to be in the House. The first was Rep. Aaron Schock (R-Ill.), elected in 2008.

Because generations are something of an obsession of mine, I decided to figure out the first member of each generation to arrive on Capitol Hill. GovTrack has data on every member of Congress in history, including birthdate (in almost all cases), and the date of their first positions on the Hill -- allowing us to determine how old each member of Congress was when he or she arrived.

Below, the make-up of new additions to the House and Senate for each Congress since 1865. I used the government's sort-of-official generation indicators for the 20th century as our primary guide, and then added two that I made up (the first two), mostly just to see how generations rose and fell over time. (Note that members of the Senate who were first in the House aren't on the graphs below, because their first Congressional jobs are reflected in the House chart.) I also called out the first members of each generation to start in each chamber.


Since we had the data, I figured it was worth looking at how the ages of members of Congress when they first arrived on Capitol Hill were distributed.


Far more members of the House, of course. But the little green dot at the far right of the Senate data is particularly interesting. Those were two members of the Senate that joined the body at the ripe old age of 86. Andrew Jackson Houston was appointed in 1941, having been born almost nine decades earlier. His appointment was because of his age; it was understood that he was unlikely to seek a full term.

The other older appointee was Rebecca Latimer Felton, the first woman to serve in the Senate -- who served for precisely one day in 1922. She was, at the time of her appointment, almost three times as old as Elise Stefanik is today.