Here at Daily Kos Elections, we’ve been keeping track of retirements from the House all year long, because a House seat without an incumbent is easier for the opposite party to win. Our spreadsheet has now been updated back to 2006, and includes seats that will not have an incumbent on the ballot in November for any reason, including losing a primary,
Comparing the pace of open seats on the Republican side to 2008 (which had the highest number of Republican open seats in decades) and 2006 (when Democrats won back the House) shows 2018 could easily beat 2008. Indeed, there are typically 10-15 more seats that open up on the Republican in the election year itself, as you can see in this cluttered figure that shows all the data back to 2006.
Democrats, on the other hand, aren’t going to be breaking any records this year, on either the low side or the high side. Come below to see the data for the Democrats, and Republicans, stretching back to 1984.
Democrats, too, are leaving the House at a faster clip than in recent years. Above, a comparison to 2010, when Democrats lost the House, and 2014, another bad year. However, Democrats have a far less consistent pattern in when they announce their departures. In 2006, 2008, and 2016, there weren’t many additional seats that opened up in the election year. These years can be seen here.
Indeed, Republicans have much less variance year to year in both the pattern and the number of open seats. Here’s the trends since 1984:
You can see spikes in retirements and resignations in 2008 and 2016. The year 2018 could easily exceed 2008; time will tell.
Democrats, on the other hand, look very different:
There was a massive spike in 1992, partly because of the house banking scandal, but also because of redistricting. Democrats managed to lose 9 House seats that year while winning the presidency. The retirements didn’t let up there, however, continuing on through 1994, which certainly helped the Republicans win the House, and 1996, when a fair number of Democrats probably decided being in the minority was no fun. The low point, on the other hand, came in 2008, with just 6 vacant seats.