If you’re interested in who’s going to control the House of Representatives next November, here’s something you need to start paying attention to: Retirement season is on its way.

So far, only four House Members have announced their retirements at the end of the current Congress, all of them Democrats and at least three of whom who give Republicans solid shots at taking their seats. That’s not many. But there are two reasons to perhaps expect more retirements than usual this time around.

The first is that Members will be running in new districts with new constituents, which often sparks retirements; for example, while only 18 Members retired in the Congress that ended in 2002, a whopping 52 retired in 1992 (helped by a silly pseudo-scandal of the time, but it’s likely that redistricting pushed many over the edge. Redistricting-based retirements are generally spread across both parties; if there are lots of retirements, then the election will (all else equal) be somewhat more volatile, and the effects of national partisan swings in either direction will likely be magnified, since open seats are more likely to be affected by the larger electoral environment.

The second possibility is that the shift in control of Congress could spark a wave of Democratic retirements. That happened after the 1994 GOP landslide, with 20 Democrats (and 13 Republicans) retiring even though 1996 eventually shaped up as a good year for Democrats. It happened again after the Democrats grabbed the House in 2006, with 20 Republicans (and only 3 Democrats) walking away going into the very good Democratic year of 2008. The idea here is that it’s just not very much fun to be in the minority in House, especially if you’re interested in actually governing, so Members tend to quit when faced with a potentially long stint in the minority. Of course, that means that a lot of this is self-fulfilling, since some of those retirements will lead to seat losses and prevent the minority from winning back the House (all data from Roll Call’s Casualty Lists).

Filing deadlines for Congressional races will be approaching in a few months in most states, and so if Members are going to retire, it’s just about time for them to start announcing it. Unlike presidential elections, where both sides have plenty of resources and all the name recognition anyone could want, House contests are often characterized by lopsided resources, and therefore candidates matter a lot — especially incumbents. So keep an eye on any retirement announcements that are made, or not made. They’re going to tell you a whole lot about which party will control the House next November.