Another Gerrymandering Game

Here's a game to practice your gerrymandering by packing and cracking. It starts pretty simple on a 3x3 board making districts of 3 blocks and builds up to a 7x7 board building 7 block districts. I am frequently a completionist on little games like this, but when you get to level 50 it will just keep going forever, so when you get there, congratulations, you won the game.


Partisan Outcome of Compact Districts

I have often been asked what the likely partisan breakdown of my maps would be. I never had the data to do that analysis, but FiveThirtyEight got the data and analyzed my maps and 7 other plans for various notions of gerrymandered and fair.
In short, my compact maps are very slightly less Republican and a bit more competitive. I've always believed that on average in the last two districtings Republicans have done more of the gerrymandering and stolen more US House seats than the Democrats have. The difference was smaller than I expected though. The difference is probably smaller than this model can usefully tell us about. All models are wrong, some models are useful, and this model is certainly not destiny but can maybe tell us something useful about the biases in the system.
FiveThirtyEight estimates that the current map has 195 safe Republican seats, 168 safe Democratic seats, and 72 competitive seats; and that this will on average elect 234.4 Republicans and 200.6 Democrats. Actually in 2016 we got 241 Republicans and 194 Democrats. 7 seats out of 435, 1.6% off, not bad.
They estimate that under my compact map that goes to 180 safe Republican seats (-15), 151 safe Democratic seats (-17), and 104 competitive seats (+32); with an expected outcome of 232.2 R and 202.8 D (D +2.2).
That 2.2 seat change looks pretty small, but I want to be optimistic about the 32 additional competitive districts. The US may be self-sorting, but while gerrymandering deliberately creates uncompetitive districts on both sides, simply not gerrymandering creates additional competitive districts. I'm not in favor of distorting districts specifically to create competitive districts (which 538 explored and created a whopping 242 competitive districts) but not deliberately creating uncompetitive districts is something I'm solidly behind. Uncompetitive districts make democracy depressing when you know you don't really have any choice, and I want this country to have more democracy.


Pennsylvania Fair District Rules

In a decision handed down on January 22, 2018 by the Pennsylvania Supreme Court, they decreed that gerrymandered districts shall be thrown out and replaced such that (emphasis mine):
any congressional districting plan shall consist of: congressional districts composed of compact and contiguous territory; as nearly equal in population as practicable; and which do not divide any county, city, incorporated town, borough, township, or ward, except where necessary to ensure equality of population. 
I stared at this paragraph for a boggled minute because the English clauses aren't clearly laid out in a prioritized order. Rationalizing it combined with what I know of redistricting law, I think the priority has to work out to be:

  1. contiguous
  2. equal population
  3. whole towns
  4. compact
If that is a complete statement of what the Pennsylvania courts want out of a district map, it's relatively simple. I clearly need to get hacking on the municipality-preserving version of my compact district solver.