Rep. Robert Pittenger (R-N.C.) managed to do something impressive Tuesday night: He broke new ground in how a House incumbent can depart the legislative body.

Pittenger lost his primary to Mark Harris, meaning that he won’t be on the ballot in November and therefore won’t be in Congress next year. While the nature of his departure from the House is unique this year (so far), that he won’t be returning is not. In fact, according to Washington Post analysis of the House’s Class of 2016, nearly 16 percent of those who won on Nov. 8, 2016, won’t be in Congress next January.

That includes 1 out of every 10 Democrats — and a fifth of the winning Republicans.

Most of those who are leaving Congress are, unlike Pittenger, leaving of their own volition. Twenty-three Republicans have announced their retirements without seeking another office. Several resigned midterm; several of them have already been replaced. A number joined President Trump’s administration.

On the Democratic side, most of those leaving office are retiring. This wasn’t always entirely voluntary on either side of the aisle. Several members of Congress announced their resignations because of scandals. The Democrats also lost a member when New York Rep. Louise M. Slaughter died.

One of the interesting factors at play in the resignations is how long those who are leaving had served in the body. On average, Republicans who won in 2016 and won’t be in the House in 2019 had served 13 years. For the Democrats, the average was 17 years. But the Republicans are also losing 10 members who had served at least 20 years. The Democrats are losing (or lost) eight members who had served that long — but the Democrats had a lot more members who had served that long. The Democrats are losing 15 percent of their delegation that has served at least 20 years. The Republicans are losing more than a third of theirs.

That’s in part a function of the Republicans faring well in House elections since 2010. It’s natural that more of their members would be new, since their gains in 2010 and 2014 were much bigger than the Democrats’ in 2012 and 2016. The average experience level of the Democrats who might return in 2019 is about 12 years. Among the Republicans, it’s eight years.

Pittenger won’t be the last sitting member of Congress to lose a primary, it’s safe to assume, and a number of sitting members of the House will also be defeated in November. Importantly, a number of seats that might normally have an incumbent who could enjoy the advantages of name recognition and established campaign teams will, instead, feature newcomers battling for the right to serve their districts.

That more of those seats were won by Republicans in 2016 is good news for Democrats.