How Gerrymandering Skewed the 2016 Elections

Jun 27, 2017

Last week, the Supreme Court said it will hear a case later this year on partisan gerrymandering—a questionably constitutional practice in which legislators draw lines of voting districts in a way that gives their party a built-in electoral advantage. The Supreme Court has never ruled on partisan gerrymandering, and its decision could have a dramatic impact on the way districts are drawn after the 2020 census.

In 2016, NHPR crunched the numbers on gerrymandering in New Hampshire and found that persistent gerrymandering over the course of 30 years has almost entirely benefited Republicans.

The Associated Press published a report this week analyzing gerrymandering across the United States and turned up a similar conclusion. The numbers indicate Republicans received a leg up from gerrymandering during congressional and state house races in 2016. The author of that report, David Lieb, spoke with NHPR’s Peter Biello.

How big of an advantage do Republicans have right now?

Well, the AP did an analysis of the 2016 elections, looking at both the state house elections across the country and the U.S. House elections across the country.

To look at the U.S. House elections first, the AP’s analysis came to the conclusion that Republicans could have won as many as 22 additional seats over what would have been expected based on their vote share in the 2016 elections.

At a state house level, that varies widely depending on what state you’re talking about. In New Hampshire, for example, Republicans also had an advantage, winning more seats than would have been expected based on their vote share.

There are some other states, Maryland for example, a Democrat-leaning state, where you would see Democrats with an advantage.

You were speaking just now about the difference between expected seat share and actual seat share. That number you’ve described as the “efficiency gap.” Can you unpack that for us, what does that mean?

The efficiency gap is a new way of measuring partisan advantage. It was developed  a few years ago by a law professor at the University of Chicago named Nick Stephanopoulos and a researcher at a public policy institute in California named Eric McGhee.

What it does, is it takes a look at this concept of wasted votes. Now, that may sound odd, but what a wasted vote is, is any vote that’s cast beyond what’s needed to win, or any vote cast for the losing party.

So let’s take an example of an election where one candidate gets 55% of the vote, and the other candidate gets 45%. Well, the party for the winning candidate has only wasted 5 percentage points of the vote, that being the difference from 50 to 55%. Whereas the losing candidate, that party wasted the full 45% of the votes.

So if you were trying to gerrymander a district, that is, draw lines that are favorable to you, what you want to do is you want to minimize the wasted vote for your own party and maximize it for the opponent’s party.

So you would want to win your races by a comfortable but close margin, maybe 55 to 60% of the votes, and you want your opponents to win fewer races, but when they do win, you want them to win by a whole lot, maybe 70 to 80% of the vote, so they’re wasting a lot of the vote.

The efficiency gap is just a statistical measurement between the amount of wasted votes for one party and the wasted votes for another party, that being the gap in how efficient they are at translating their votes into victories.

To what extent is the efficiency gap part of the reason the Supreme Court is deciding to take on this case that’s originating in Wisconsin, this political gerrymandering case?

So, historically, the Supreme Court has ruled on gerrymandering cases from a couple of perspectives. It’s addressed racial gerrymandering, where African-American voters are perhaps spread too thin or packed too close together in a district to really get a lot of say out of their votes, to elect a candidate of their choosing. Or, the Supreme Court has looked at cases where districts are of unequal population.

In the Wisconsin case, a federal appeals court did something different. They said that the districts were gerrymandered in a partisan way, that is, they were drawn by Republicans to the disadvantage, intentionally, of Democratic-inclined voters.

Now, the Supreme Court, in the past, has been reluctant to adopt a threshold of when partisan gerrymandering crosses the line from just normal politics to unconstitutional. That’s part of what’s at issue in this Wisconsin case.

The Wisconsin case did cite the efficiency gap as corroborating evidence in ruling that there was an intentional partisan gerrymander. Now it’s at the Supreme Court to decide whether partisan gerrymandering is in fact something that can be unconstitutional. And if the Supreme Court upholds that decision in Wisconsin, it could have ramifications for states across the country.

Do  you expect that the Supreme Court will look at the efficiency gap as the standard by which they determine whether gerrymandering has been done in a partisan way?

Well, the efficiency gap has certainly been argued in the briefs as a measure of partisan advantage. The Supreme Court could take a look at that and say the efficiency gap is one thing we could use. There are also other statistical measures it could take a look at. That is really one of the issues that’s up in the air, whether the Supreme Court will adopt a specific standard to measure partisan gerrymandering, or not.

You looked at all fifty states in your report. How did New Hampshire fare, according to your metric?

New Hampshire, as you know, has a lot of seats in its State House of Representatives. And because of that, it comes up with a lot of excess seats for Republicans. New Hampshire actually ranked sixth nationally, I believe, in terms of its Republican partisan efficiency gap advantage. That is to say that Republicans enjoyed an advantage there beyond what would be expected.

If you take that efficiency gap and you translate it to the number of excess seats that Republicans may have won, it comes out to about 23 additional seats that went to Republicans beyond what would have been expected based on their share of the vote.

Now, in New Hampshire, the share of the vote was almost 50-50. The Republicans had maybe 50 to 51% of the statewide vote, based on their district averages, Democrats about 49 and a half percent. As it stands, I think the Republican advantage in that chamber is about roughly fifty seats, give or take. If you flipped 23 of those seats, you would have a chamber that’s would be much closer along its partisan division.