October 31, 2018

Michigan Gerrymandering Proposal

In the upcoming election, in Michigan there is a proposal to change the way that districts for congressional elections are created (Proposal 2).

Currently, the map of districts is drawn by the state legislature. In 2010 there was a backlash from the Obama administration and the Republicans took complete control of the Michigan legislature. They then proceeded to draw some questionable districts which favor the Republican incumbents, and so even though the State elects Democratic senators the Republicans control a large majority of Michigan's delegation to the House of Representatives.

The proposal on the ballot would change this so that an "independent committee" would instead draw the district lines.

I thought it would interesting to see how different the map would look if made in a way that was not so partisan. First, let's take a look at the current district map.


Some things to note:
  • Districts 2 and 3 meet in the Grand Rapids area, the way that the line is drawn makes both districts lean strongly Republican, since the Democrat leaning areas are split. If the line was straight then district 3 would be more of a toss-up.
  • Districts 4 and 10 lean Republican, all of the Democrat-leaning areas of Flint, Saginaw, and Bay City were combined into one district to make the other two strongly Republican, rather than having 3 toss-up districts.
  • District 8 includes most of the very left-leaning Lansing, but conveniently stretches around the top of the Detroit suburbs to reach the right-leaning Rochester Hills, making a consistently Republican district.
  • The way districts 9, 11, and 14 spiral around each other just screams Gerrymandering.
So I made my own map. First I tried to follow county lines as much as possible, grouping adjacent counties together to get close to the population of a representative district, and only splitting up counties that contained a higher population than allowed in a district (Macomb, Oakland, and Wayne counties). This worked nicely, getting each district pretty close to the right population. The result is shown below.

The lines around the Detroit area within counties I left rather vague, for the actual map a similar approach would be taken, trying to follow city and township lines to make the district as compact as possible. For example, Macomb county has its population concentrated at the south end, so the actual line would be much farther south.

My initial guess would be that Democrats would control districts 8, 12, and 13, Republicans would control districts 1, 2, and 9, and that there would be more of a toss-up in the other eight districts.

Update: The redistricting will take place after the next census. Estimates are showing that Michigan will lose one congressional district. So I decided to make a second map using only 13 districts.