Are you upset about the fact that the Presidential race is set up to allow the possibility that the candidate with fewer popular votes might still win? For example, Gore won by about 0.5% more votes – yet Bush became President. Depending on specific conditions, this “lumpiness” can help one Presidential candidate or the other. As it turns out, the structural change in House districts creates a problem similar to these – but larger, and in one direction only.
Previously I gave a detailed calculation regarding the state of House races. Today’s essay is shorter, though still geeky. You may have an epiphany about our democracy…or decide to see what is happening at The Onion.
The entire story is contained in this one graph.
The black line is my estimate of where the playing field is. The red line shows the range where I thought the race would end up – though note that events are overtaking this somewhat. More on that in a bit.
Each point represents one Congressional election since 1946, with an arrowhead (^) pointing at the most recent one. The gray shading shows the area covered by the data, and gives an idea of what used to be considered likely or possible. The gray region crosses diagonally through (0,0), which means that in the past, winning the popular vote usually meant winning control of the House. Until now.
Here is what I did, skipping most of the math.
(1) First, I had to figure out how votes would translate into seats in 2012. That is shown by the black diagonal line which skirts the bottom of the gray region. Notably, it does not go through (0,0). Compared with history, Team GOP now has an advantage about equivalent to getting a 2.5% extra popular vote share across the board. This advantage comes from partisan redistricting plus incumbency, a powerful combination. The low slope of the diagonal is another likely consequence of redistricting – seat count is less sensitive to vote outcomes.
The difference between 2.5% and zero is substantial. Many fans of U.S. politics like to go on about the unfairness of the Electoral College. However, that problem is less than 1%, and averages out to zero. Redistricters cannot take Philadelphia out of Pennsylvania and stick it into New Jersey. But House districts are a different matter.
An advantage of this size is unprecedented…almost. The one data point below the diagonal is 1996. Analysts often cite 1996 as a strange year: Democrats won the House popular vote, but Republicans retained control. Well, from now on, every election for the next ten years is potentially like that. It’s like global warming: previously extreme events will now become routine.
If anyone thinks I am underestimating this effect, do tell. I am all ears. But please read “The Very Hungry Gerrymander” (Oct. 4) first.
Now to the popular vote.
(2) To estimate the likely popular vote on November 6th, I used the generic Congressional ballot to predict a D+2.5+/-3.0% popular vote win. That is shown as a red line segment along the diagonal. This is the weak point of the argument, because the popular vote is a hard thing to predict.
I do not think there will be a “wave election” – a mass eviction of incumbents. The real wave election was in 2010, when the GOP won the national popular vote by 7%. Compared with that, the pendulum is certain to swing back a bit. But by how much?
The estimable Charlie Cook thinks the House is unlikely to flip, largely based on current district-level data. Keep an eye on him to see if his estimate changes.
Where will conditions end up on November 6th? As you can see in the Meta-Margin, the Obama campaign took a 5-point hit last week after the debate, and is now below Obama+1%. Re-elected Presidents have coattails, and the House popular vote is said to follow the Presidential vote closely. The tightening of the Presidential race suggests that the result will be closer to the left end of the red line segment. Or it could come back. Suspenseful!