New paper shows just how badly gerrymandered Wisconsin is

Here is a timely and interesting study on Wisconsin’s gerrymandered legislative maps, which are on trial in a federal courtroom starting today. It comes in the Washington Post’s wonky “Monkey Cage” section, and was done by 5 Binghamton College PoliSci professors and graduate students using election data in Wisconsin’s statewide elections from 2008 to 2014, then overlaying those results with the current Assembly legislative districts.

Here are the baselines that the study started with.

For those who haven’t looked at statistics in a while, we get “mean” vote across assembly districts by adding each party’s percentage of the vote in each district and dividing by the number of districts, or 99. The “median” district vote, by contrast, is what we could get if we list the districts from most Democratic to most Republican (by percentage of the vote) and choose the one exactly in the middle. The mean and median should be nearly the same in a fair system.

If the median district is only 45 percent Democratic, then the chances of a Democrat winning it is slim – and therefore the Democrats are very unlikely to win a majority of the legislature. In this case, if the mean district was also 45 percent Democratic, there’d be no bias in the system and the Dems would be getting what they deserve when they fail to take control of the assembly.

Then the Binghamton researchers created a “neutral” Wisconsin Assembly map from a computer program which requires only that 1. districts be contiguous and 2. have the same population. This would test to see if the fact that the heaviest Dem voting districts (large parts of the cities of Milwaukee and Madison, and the Menominee Reservation) are more pro-Dem than the heaviest pro-GOP districts in the state would give the GOP a natural gerrymander through “the big sort” of population.

What that simulation proved that Wisconsin’s pro-GOP gerrymandering was not only no accident, it was also significant.

These neutral maps show a natural gerrymander of 1.1 to 3.9 percentage points (using the same median-mean comparison) favoring the Republicans. Obviously, this is smaller than the total bias of 3.8 to 6.3 percentage points in the current map. What is extraordinary is that none of the 10,000 neutral maps produced a plan as skewed toward the Republicans – in any of the 13 statewide elections from 2008 to 2014 that we examined — as the actual map drawn by the state assembly.

Or to think about it differently, Wisconsin’s state legislative districts were drawn to add an additional, thick layer of bias atop the “natural” gerrymander of where Republicans and Democrats live in the state.

And it’s the severity of the gerrymander that this lawsuit is based on, that many Wisconsinites are disenfranchised from a fair chance to pick who represents them because of these manufactured district maps.

The article also has a very cool chart (click here to see it) that illustrates the “natural” and “GOP-made” gerrymanders in Wisconsin. It’s interesting to see the size of GOP bias grow between the 2010 and 2014 statewide elections, for both the gray and red lines, which indicates the increasing level of polarization in the state in the Age of Fitzwalkerstan, and less 50-50 areas in general.

That chart also illustrates how much of a landslide is needed to flip the State Assembly into Democratic control- a uniform swing during a statewide total in the neighborhood of President Obama’s 56-42 win over John McCain in 2008. That’s a lot to overcome in a state where Republicans have a large amount of their voters getting their “facts” from biased news sources that won’t tell dare reveal what is really going on outside the Bubble (you’d think the fact that Ted Cruz turned into a punchline after the Wisconsin primary would make them think about it, but nope!).

So let’s see if we can get some new ground broken in this week’s redistricting trial, which already has been given enough credence to have the argument heard in court in the first place. If these maps can be thrown out or even forcibly modified (how can the Madison areas have non-contiguous “islands” of certain districts?), it’ll send a wake-up call to an arrogant Wisconsin GOP who figures these rigged maps will save them regardless of what kind of heinous legislation they choose to pass.