Princeton Election Consortium

A first draft of electoral history. Since 2004

Tom Petty

October 3rd, 2017, 6:36am by Sam Wang

This was the first Tom Petty song I loved.
So much bad news in the world. The biggest mass shooting in U.S. history. The rapid erosion of norms in our government’s institutions. Climate change-induced intensification of hurricanes, and the ensuing disaster in Puerto Rico. The post-apocalyptic imagery in the video above seems fitting.

However, there is a bright spot: U.S. science. Rosbash, Hall, and Young richly deserve their Nobel Prize for working out the genetics and molecular mechanisms of circadian rhythms. Surely every one of you has an opinion about whether you got enough sleep last night. Circadian rhythms are a central feature of our lives, and are critical for health. Their work was done in a small fly, Drosophila melanogaster, and the basic principles all apply to us. This prize, for molecular neuroscience, is a pinnacle of basic research, one that was made possible by the greatness of American scientific establishment.

Today, the Nobel Prize in Physics goes to Weiss, Thorne, and Barish, for the discovery of gravitational waves. Again, a milestone in basic research.

Off to the Supreme Court, to see whether (statistical) science cuts any ice with them.

→ 1 CommentTags: 2014 Election

Gill v. Whitford

October 1st, 2017, 12:08pm by Sam Wang

On Tuesday at 10:00am, the Supreme Court will hear oral arguments in the case of Gill vs. Whitford, which concerns extreme partisan gerrymandering. Justice Ginsburg has suggested, with some justification I think, that this could be the most important case of the Court’s term. The tone and content of oral arguments are often predictive of the outcome. I will attend in person. And of course I will be watching the leaderboard at FantasySCOTUS.

As PEC readers know, my interest arises from my analysis which offers a standard that meets legal constraints set in place by the Court. Read our amicus brief or watch our great explainer video. For a deep dive into why partisan gerrymandering has soared, see our piece in The American Prospect.

The outcome is likely to hang on the vote of Justice Anthony Kennedy. To quote Amy Howe of SCOTUSblog:

…the state’s ability to muster the five votes that it needed to put the lower court’s order on hold could bode poorly for the challengers, because one factor that the justices had to consider in making their decision was whether the state is likely to succeed on the merits of its claim. On the other hand, the case appears to have been scheduled for oral argument earlier than it might normally have been: Although the justices did not announce until June 19 that they would review Gill v. Whitford, it leapfrogged over several other cases (including two granted in February, two granted in March and one granted in April) to take a spot on the October argument calendar. That could suggest that the justices intend to try to decide the case quickly, which would in turn allow new maps to be drawn sooner even if the district court’s order is not in effect.

Attendees are not allowed to speak in the courtroom. Otherwise the bingo card above could help while the time away!

→ 9 CommentsTags: Redistricting

Job opportunity – Computational Research Analyst, Gerrymandering and Redistricting

September 28th, 2017, 11:57pm by Sam Wang

The Gill v. Whitford oral argument gives new importance to this announcement. -Sam, 10/4/2017

The Princeton Gerrymandering Project is hiring! We’re looking for a computational research analyst to do geography-intensive calculations, test our simple statistical standards, and close loopholes in proposed reform efforts. It’s a full-time position, available immediately. Computational skills and an interest in U.S. election law are essential. The job ad is here.

→ 4 CommentsTags: Redistricting · Site News

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. If you need technical assistance, please write to

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

→ 7 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.

→ Post a commentTags: Redistricting · U.S. Institutions

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…

→ Post a commentTags: Redistricting