In the House: as of April 11, there were 55 total not seeking re-election, plus two resignations, for 57 total -- which was a near record. I'm not sure if any others were announced since this article.
The record is still held by the year 1992, which had 65.
Here is the article from Pew Research. Here is an Atlantic magazine list.
How many Senators have resigned or are not seeking another term?
Here is the list, which includes the House and Senate, from which I got this list of the Senate:
Very nice link.
That could be it’s own thread, almost.
Great post love the link