Princeton Election Consortium

A first draft of electoral history. Since 2004

Meta-Margins for control: House D+1.0% Senate R+4.2% Find key elections near you!

Three clues that today’s proposed Pennsylvania map is still a gerrymander

February 10th, 2018, 4:38pm by Sam Wang


An image of the Pennsylvania legislature’s proposed Congressional map has been released. It appears to be nominally in compliance with the Pennsylvania Supreme Court’s order, since it splits fewer counties than the current map. However, as we have seen in North Carolina, a prettier map can still conceal ill intent.

Despite the low resolution, enough information is available to conclude that this is still a partisan gerrymander. Of course one can do a detailed partisan calculation, and Dave Wasserman thinks that it’s still 12 R, 6 D, and Nate Cohn thinks it’s 13 R, 5 D. It is absolutely central to remember that even under compactness-based rules, a wide range of partisan outcomes is possible – and this plan is extreme.

Even without making such seat-based calculations, three clues indicating a gerrymander are apparent:

1) Packing and cracking. A display of population density reveals that some districts enclose high-density areas (Pittsburgh in Allegheny County, and Philadelphia), while other lines split densely-populated communities down the middle (see the Scranton, Harrisburg, and Reading areas). Because Democrats tend to be abundant in high-density areas, this is a sign of how they were packed and cracked.

2) Majority-minority districts. According to news reports, Pennsylvania Republican legislators are touting the fact that this map has two districts (PA-1 and PA-2) that are majority-black, thus complying with the Voting Rights Act. However, because whites split between Republicans and Democrats, it’s not necessary to pack that many blacks into a district in order to give them a shot at electing someone. These days, it’s only necessary to create an “ability-to-elect” district with, say, 30-40% black voters. That generates a district that is safe for blacks (and thus Democrats) without wasting too many votes – similar to the safe districts that Republicans draw for themselves. Such symmetry would pass our lopsided-wins test, and treats the two parties equally.

3) The process was skewed. Democratic legislators were frozen out of the process. If the intent was to strike a bipartisan balance, that would not have occurred. Single-party control does not favor balanced outcomes.

Based on these three bits of evidence, it appears that Republicans are not dealing in good faith with the Pennsylvania Supreme Court’s order.

Tags: 2018 Election · Redistricting

6 Comments so far ↓

  • Daniel

    Dr. Wang,

    I have followed your site irregularly since the 2014 elections and am truly glad you are delving into elements of our democracy that have (somehow, almost inconceivably) gone unchecked for so many years . Your co-authoring an amicus brief on the case at the center of all this is also inspiring.

    This recent news is truly unfortunate and, unsurprisingly, predictable. I could be wrong, but I suspect the court will end up redrawing the map and partisan bitterness will ensue from there. My only hope is that any chaos will be contained and not contribute further to the collapse of democracy. Aside from the case possibly going to the Supreme Court, do you have any thoughts on what may happen (culturally, politically, etc.) if the PA court draws the map?

    • Sam Wang

      I think this is just a bad moment in this particular dispute. Things will be fine in a few weeks. The partisanship of the “solution” is plain, and the Pennsylvania Supreme Court will draw a fairer map. There are quantitative, neutral tests that will prove it. See the Vox piece we wrote recently.

    • LondonYoung

      I presume the governor just vetos the plan and the court draws their own map.
      But in the bizarre case where the governor were to sign it, would the court accept it?

    • Sam Wang

      My guess is that the court would reject the plan. In any event, both the court and the governor have retained good experts, so the legislature’s proposed plan is unlikely to become law.

  • 538 Refugee

    “Based on these three bits of evidence, it appears that Republicans are not dealing in good faith with the Pennsylvania Supreme Court’s order.”

    All they care about is giving their preferred news outlet some talking points.

    Am I being too cynical?
    http://www.newsweek.com/liberals-dont-share-believe-fake-news-much-right-wing-study-finds-800219

    • LondonYoung

      There is nothing cynical about observing the fact that liberals average much better educated and are thus less likely to fall prey to fake news than conservatives.

Leave a Comment