Less than 10 percent of House in 2023 will have been elected in 20th Century

Amid the flurry of retirements and primary defeats this cycle, Congressional turnover will continue in November.

When the dust settles after Election Day, between 36 and 40 members of the House will be left who took office in the 20th Century (four incumbents are in races rated competitive by The Cook Political Report with Amy Walter). In the Senate, eight incumbents elected to their posts in the 20th Century are slated to return, with an additional two in competitive races.

Much of that turnover has happened in the last 12 years, particularly on the GOP side. Depending on the outcome of competitive races, up to 96 members of the House who took office before 2011 (seven are in Cook Political Report-rated races) — up to 59 Democrats and 36 Republicans.

On the flip side, this cycle will likely bring the first member of Generation Z to Congress — Democrat Maxwell Frost, who won the primary in a Democratic-leaning seat in Florida and is the favorite to win his election. And New Hampshire Republican Karoline Leavitt is running in New Hampshire, where she could flip a seat for the GOP.

Both would be 25 when they take office, if they win.

For more on on what the makeup of Congress might be after the election, and other dynamics driving the midterm elections, check out the NBC News Political Unit’s Election Book.