Princeton Election Consortium

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New Dataset: State Legislative Elections, 1971-2016

September 26th, 2017, 12:00pm by brian

I’m pleased to say that the Princeton Gerrymandering Project has just published a new dataset of state legislative elections from 1972 to 2016. This database covers over 500 election/state/year combinations, and contains over 80,000 elections. The election results can be downloaded here, and the code can be viewed on github. The dataset is based on Carl Klarner’s candidate-level state legislative data, cleaned to remove multi-member elections and other issues, as well as Ballotpedia’s 2013 – 2016 election results.

For us, it’s a resource to analyze redistricting and gerrymandering. For you, it’s whatever you want to use it for.

We’ll eventually combine these with information about the district maps under which each election was held. Stay tuned!

→ 5 CommentsTags: Redistricting

The Very Hungry Gerrymandering Project

September 25th, 2017, 6:48pm by Sam Wang

Left: Eric Carle's caterpillar. Right: NC 12th District Gerrymandering comes to the forefront. See for a video about standards for extreme partisan gerrymandering that we are advocating, based on simple concepts of partisan symmetry and basic statistics. The explainer is pretty spiffy!

Want to know how gerrymandering has gotten so bad in the last few decades? Here’s a history (with numbers) in The American Prospect. A sidebar explains the math.

Finally, we have an interactive website for you to explore the offenses: It documents Congressional and state-legislature gerrymanders, including Wisconsin Assembly, the topic of next week’s oral arguments before the Supreme Court in Gill v. Whitford.

We hope you enjoy these explorations!

→ 6 CommentsTags: Redistricting

When did partisan gerrymandering get worse, and why?

September 25th, 2017, 7:22am by Sam Wang

Partisan gerrymandering: when did it get worse, why, & what can courts & reformers do? New at The American Prospect, we trace the roots of an offense that has ballooned in recent decades.

Also, over at the Princeton Gerrymandering Project, we’ve added state legislative data. This includes data for the Wisconsin Assembly, which is important for next week’s Supreme Court case. Thanks to Rob Whitaker!

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A tutorial on partisan gerrymandering

September 7th, 2017, 8:45am by Sam Wang

Here’s a spiffy explainer video on how extreme partisan gerrymandering is committed, and how it can be detected by anyone who’s ever taken a basic statistics class.

Many thanks to the creatives behind this, Kyle McKernan and Danielle Alio of the Princeton University communications office. If you like their work, share it and “like” it!

→ 9 CommentsTags: Redistricting

A Manageable Approach to Partisan Gerrymandering

September 4th, 2017, 2:22pm by Sam Wang

If the Supreme Court lays down a partisan symmetry-based standard for gerrymandering, will this open up a flood of lawsuits? Over at Election Law Blog, I use election evidence to argue that no, it will act as more of a brushback to future offenders.

The reason? As you can see in the chart, partisan gerrymanders only took off starting in the 2000 redistricting cycle, at the same time that it began to be thought that they were legal. Before then, they were considerably less common.

Thanks to Rick Hasen for hosting the essay, and to Brian Remlinger for data analysis.

→ 1 CommentTags: House · Redistricting

Amicus Brief in Gill v. Whitford

August 30th, 2017, 10:39pm by Sam Wang

Today we submitted our amicus brief (read the PDF) in the case of Gill v. Whitford. The authors are Heather Gerken, Jonathan N. Katz, Gary King, Larry Sabato, and me. In it, we argue that the Supreme Court should define basic fairness in redistricting using the concept of partisan symmetry. We use this idea to suggest simple statistical tests that could be used as a manageable standard to identify extreme partisan gerrymandering.

For example, are Democratic districts more packed than Republican districts than would be expected from inadvertent effects? That can be determined using Student’s t-test, the most common test in the sciences, invented by an experimental brewer at the Guinness Beer Company over 100 years ago.

If the Court accepts our recommendation, then there would be, for the first time, a way for courts to say when a partisan gerrymander has gone too far. This has been an unresolved issue since the mid-1980′s, when the Court first said that partisan gerrymandering was a violation of the U.S. Constitution. Now that partisan gerrymanders have become rampant in the last redistricting cycle, we believe it is time for the Supreme Court to act.

If you want to learn more about symmetry standards, I invite you to visit the Princeton Gerrymandering Project. You can also support our work here.

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Gerrymandering vs. Math: Who will win?

August 29th, 2017, 2:23pm by Sam Wang

From Emily Bazelon, a sharp look at partisan gerrymandering. Her thinking and analysis will resonate with fans of the Princeton Gerrymandering Project.

We’ll have more coverage soon, once the Supreme Court amicus filing deadline has passed…

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Democratic Partisan Gerrymanders, 1972-present

August 23rd, 2017, 12:39am by Sam Wang

The Princeton Gerrymandering Project makes it easy to browse all gerrymandering offenses for a given year. We are now starting to cross-reference these offenses with who had control over the redistricting process. It’s a daunting task, but our statistical analyst Brian Remlinger is on the case.

Brian has found something interesting: from 1972 until now, Democratic extreme partisan gerrymanders are surprisingly rare. What’s going on? [Read more →]

→ 4 CommentsTags: House · Redistricting

Politics & Polls: Charlottesville and our broken public discourse

August 17th, 2017, 12:09pm by Sam Wang

The route between public outrage and consequences for President Trump seems quite broken. Why? Julian Zelizer and I chew it over in the new Politics & Polls. The opening is especially lively. Later we get into the regular nerdery.

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The Princeton Gerrymandering Project is live!

August 4th, 2017, 7:34am by Sam Wang

I am happy to announce our revamped site at This is part of the Princeton Gerrymandering Project’s tooling up for the coming several years of work by courts and reformers.

The site now has an interactive map showing the results of three simple gerrymandering tests, applied in all the states. It allows you to upload data more conveniently than before. Finally, it has a tutorial, as well as links to background reading and current court cases. Check it out!

All of this was done by the team: Rob Whitaker, Brian Remlinger, Aimee Otsu, Sung Chang, and Naomi Lake. Hats off to their great effort.

→ 11 CommentsTags: Redistricting · Site News