a lesson in history
The 115th Congress began on Jan. 3, 2017, and in the time since, 12 of its members have resigned. That's the largest group of resignations for any congressional session since 1901, FiveThirtyEight reports, and this winter's spate of sexual misconduct allegations is responsible for the record attrition rate.
Some of these resignations are normal. A new presidential administration typically means a handful of sitting members of Congress will resign to accept Cabinet and other agency chief roles.
But three resignations over allegations of sexual misconduct in a single Congress is so not normal that FiveThirtyEight argues this data point justifies the conclusion that "we are in the midst of an unprecedented cultural moment" with the #MeToo movement. Just 3 percent of congressional resignations since 1901 were publicly linked to sex scandals, so three in one session is a lot. (That count excludes members who have not resigned but instead announced they will not seek re-election.)
Check out the full analysis here for a breakdown of all the reasons 615 members of Congress have left their posts in the last 117 years.