Who Gerrymanders More, Democrats or Republicans?

For indispensable reporting on the coronavirus crisis and more, subscribe to Mother Jones' newsletters.


A couple of months ago I linked to a bit of research showing the effect of gerrymandering on House races. Long story short, Eric McGhee concluded that gerrymandering produced about 7 extra Republican seats this year while Sam Wang figured it at about 6.3 seats. A few days ago, Sam took a deeper dive into the data (read his full post if you want to understand his simulation methodology) and came up with a bit more detail about how that breaks down. His bottom line number is now slightly higher than it was before, showing a Republican advantage of about 7.1 seats, but the reason this number is so low is a little surprising. I’ve modified his main results table a bit for the nine states that show a substantial discrepancy between vote share and seat share. Here it is:

  D %vote D sim R sim D seats R seats Discrepancy
Pennsylvania 50.7% 8.4 9.6 5 13 R+3.4
Texas 39.9% 9.4 26.6 12 24 D+2.6
Ohio 47.9% 6.5 9.5 4 12 R+2.5
North Carolina 50.9% 6.2 6.8 4 9 R+2.2
Michigan 52.7% 7.2 6.8 5 9 R+2.2
Arizona 45.6% 3.2 5.8 5 4 D+1.8
Virginia 49.0% 3.7 5.3 2 7 R+1.7
Illinois 55.4% 10.3 7.7 12 6 D+1.7
Indiana 45.8% 3.2 5.8 2 7 R+1.2
Nonpartisan           D+4.4
D-controlled           D+1.7
R-controlled           R+13.2
Net, all 9 states 48.5% 58.1 83.9 51 91 R+7.1

There was serious gerrymandering in only one Democratic state: Illinois, for a total advantage of 1.7 seats. But there was serious gerrymandering in six Republican states, for a total advantage of 13.2 seats. Republicans tried hard to gerrymander themselves into a majority, but it turned out that two nonpartisan states (a commission in Arizona and a court in Texas) ended up producing 4.4 extra Democratic seats.

Bottom line: The net result is still fairly modest, thanks to the vagaries of nonpartisan redistricting. At the same time, the effect of partisan gerrymandering is larger than we thought. The sum of Democratic and Republican gerrymandering is a net Republican advantage of 11.5 seats. That’s still not enough to say that the Republican House majority is solely due to gerrymandering, but it’s close.

Thank you!

We didn't know what to expect when we told you we needed to raise $400,000 before our fiscal year closed on June 30, and we're thrilled to report that our incredible community of readers contributed some $415,000 to help us keep charging as hard as we can during this crazy year.

You just sent an incredible message: that quality journalism doesn't have to answer to advertisers, billionaires, or hedge funds; that newsrooms can eke out an existence thanks primarily to the generosity of its readers. That's so powerful. Especially during what's been called a "media extinction event" when those looking to make a profit from the news pull back, the Mother Jones community steps in.

The months and years ahead won't be easy. Far from it. But there's no one we'd rather face the big challenges with than you, our committed and passionate readers, and our team of fearless reporters who show up every day.

Thank you!

We didn't know what to expect when we told you we needed to raise $400,000 before our fiscal year closed on June 30, and we're thrilled to report that our incredible community of readers contributed some $415,000 to help us keep charging as hard as we can during this crazy year.

You just sent an incredible message: that quality journalism doesn't have to answer to advertisers, billionaires, or hedge funds; that newsrooms can eke out an existence thanks primarily to the generosity of its readers. That's so powerful. Especially during what's been called a "media extinction event" when those looking to make a profit from the news pull back, the Mother Jones community steps in.

The months and years ahead won't be easy. Far from it. But there's no one we'd rather face the big challenges with than you, our committed and passionate readers, and our team of fearless reporters who show up every day.

We Recommend

Latest

Sign up for our newsletters

Subscribe and we'll send Mother Jones straight to your inbox.

Get our award-winning magazine

Save big on a full year of investigations, ideas, and insights.

Subscribe

Support our journalism

Help Mother Jones' reporters dig deep with a tax-deductible donation.

Donate

We have a new comment system! We are now using Coral, from Vox Media, for comments on all new articles. We'd love your feedback.