Gerrymandering Isn’t Giving Republicans the Advantage You Might Expect

There is no shortage of reasons Republicans are expected to retake the House this year, including President Biden’s low approval ratings and the long history of struggles for the president’s party in midterm elections.

But there’s another issue that looms over the race for the House, one that doesn’t have anything to do with the candidates or the voters at all: the fairness of the newly redrawn congressional maps.

You might assume that the House map is heavily gerrymandered toward Republicans, especially after Republicans enacted aggressive gerrymanders in critical states like Texas and Florida. Many of you might even presume that this gerrymandering means that the House isn’t merely likely to go to the Republicans, but that it’s also out of reach for Democrats under any realistic circumstances.

In reality, Republicans do have a structural edge in the House, but it isn’t anything near insurmountable for the Democrats. By some measures, this is the fairest House map of the last 40 years.

Here’s one way to think about it: If you believe Democrats have a good chance to win the Senate, they ought to at least have a chance to win the House — even if Republicans are favored there.

Let’s start with a simple fact: On the new House map, 226 districts would have voted for Mr. Biden in 2020, compared with 209 for Donald J. Trump.

Now, Mr. Biden won the national vote by 4.5 percentage points, so even a map that’s biased toward Republicans might still have more Biden districts than Trump districts. But the simple fact that Mr. Biden won the most districts is a clear enough indication that the Republican advantage in the House isn’t totally insurmountable.

To account for Mr. Biden’s victory in 2020, a somewhat better — though more complex — measure is needed: a comparison between how districts voted and how the nation as a whole voted. If Mr. Biden won a district by more than he did nationally, it might be said to be a district where Democrats have the advantage if the national vote is tied. On a perfectly fair map, half the districts would lean toward Democrats with respect to the nation, while half would vote for Mr. Trump or vote for Mr. Biden by less than 4.5 points. And on this perfectly fair map, the district right in the middle — the median district — would have voted for Mr. Biden by 4.5 points, just like the nation.

So what does this House look like by those measures? The median district backed Mr. Biden by 2.1 points, a little bit more to the right of the nation as a whole. And overall, there are 215 districts where Mr. Biden won by at least 4.5 percentage points, compared with 220 districts where Mr. Trump won or where Mr. Biden won by less than 4.5 points.

Both of these measures show a map tilted toward Republicans. To retain control of the House in our hypothetical, Democrats would need to win at least three districts where Mr. Biden did worse than he did nationwide, including a district where he won by 2.1 points or less. Republicans could theoretically prevail by defending districts where Mr. Trump won or lost by less than he did nationwide.

This is a real Republican edge, but it is not a daunting one for Democrats. Here are three ways to put it in perspective.

First, the Republican edge is flimsy. In a chamber with dozens of competitive races, a three-seat advantage just isn’t that much. If Republicans nominated a few too many unelectable stop-the-steal candidates or if a few too many Democratic incumbents proved too resilient, the Republican structural edge would evaporate.

Second, the edge is historically small. In fact, there are more Democratic-tilting districts — 215 — than at any time in the last 40 years.

As recently as 2012, there were just 195 districts where Barack Obama had fared better than average nationwide in the prior election. That was such a large advantage that you really could (and I did!) dismiss the possibility of a Democratic win anytime soon, even if the party could narrowly win the House popular vote. Not anymore.

Third, the Republican structural advantage is fairly comparable to that of the Senate and the Electoral College — two bodies where, yes, the Republicans command structural advantages, but where no one really questions whether the Democrats can win.

Consider this: While Democrats could win the House by carrying every district that Mr. Biden won by at least 2.1 points, the Democrats would lose the presidency and the Senate if they only won states where Mr. Biden won by 2.1 or more. In the Senate races, Georgia and Arizona seats would flip to the Republicans, while Democrats would fail to flip seats in Pennsylvania, Wisconsin, North Carolina and Ohio.

Or put differently, if Democrats can win the House races that resemble Senate contests in Arizona, Georgia, Pennsylvania and Nevada, they can probably win the House.

There is one catch in this comparison, and here’s where gerrymandering comes into play: Democrats will need to win a higher proportion of competitive districts than they do in the Senate.

For illustration, let’s define a “competitive” state or district using what we’ll call the North Carolina-Virginia range — meaning identifying every district that voted between Mr. Trump’s 1.3-point victory in North Carolina and Mr. Biden’s 10.1-point win in Virginia. This is a convenient measure because both states diverged roughly 5.7 points from the national vote in 2020, North Carolina to the right and Virginia to the left.

To win the Senate this year in our scenario, Democrats would need to win four of the seven races in the Virginia-to-North Carolina range. To win the House, Democrats would need to win about 72 percent of the districts in that Virginia-to-North Carolina zone, or five in seven races.

Winning five of seven competitive seats is a tough burden for Democrats, especially in a midterm year. But is it impossible? It certainly isn’t impossible for Democrats to win five of the seven key Senate races — in fact, Democrats might well be the favorites in five of the seven Senate races right now. A similarly impressive run in the House might be more of a challenge, but Democrats would bring many of the same advantages to the table — like stop-the-steal Republican nominees and a disproportionate number of Democratic incumbents.

None of this means Democrats are going to win the House. But if they don’t, it may not be so simple to blame gerrymandering.