2020 Census and Redistricting Thread: Michigan

[palandio]

Monroe + Southern Wayne is a pairing that seems very natural to me and I was wondering why it was so rare in the maps that were posted so far.

The challenge I can see is to draw a Monroe + Southern Wayne district without splitting the Middle Eastern communities in e.g. Dearborn, Livonia and other areas.

[palandio]

Okay, take two I suppose :-)

https://davesredistricting.org/join/06892011-f81c-439d-ab87-79c4f50589f8

[...]

Generally many good choices and decisions. I would criticize the following:
- Putting Livingston County with Lansing continues Slotkin's current district, but it is otherwise ugly. It combines Detroit ex-urbs with an independent metro and is therefore not good from a CoI perspective. Instead Jackson could go with Lansing and Livingston County with Washtenaw.
- Separating Kalamazoo and Battle Creek is often difficult to avoid, but it's still not nice. I would slightly rotate districts 1, 2, 5, 6, 7 and 10 in the following way: 7 would take most of Calhoun County (Battle Creek) from 6, 6 would take from 5, 5 from 10, 10 from 1, 1 from 2 and 2 from 7.

[palandio]

CoI-wise Washtenaw is the odd child, it's about half a district, but most potential partners don't really fit. SW Oakland and far NW Wayne could fit relatively well, although that probably creates problems for the rest of the map. The seat that includes Ann Arbor will be a bad CoI on most maps.

The Flint-Saginaw seat can always include Bay City if you accept connecting the Thumb to the Northern Hudson shoreline via the beach of Bay County. (Yes, I know, it's ugly.) What you seem to propose is a district combining the Thumb with Northern and Central parts of Macomb like the current 10th. This district would be nice and compact, but also prevent a Macomb seat and pair major metro Detroit areas with major non-metro areas.

[palandio]

Yes, as a CoI it's awkward, but it stays mostly in metro Detroit and it leaves space for a nice-shaped Lansing-Jackson seat to its West (or alternatively Kalamazoo-Battle Creek-Jackson). It might be the least bad solution.

[palandio]

I gotta say, the reluctance to put Southfield in a Detroit based district from some of y'all baffles me. Not so much from the folks who have been consistently on the record opposing VRA districts or obsessing about county contiguity, but moreso from people who will usually dismiss county considerations in favor a California-style CoI approach. Southfield is literally right there and is prime fodder for a thoughtful map's 2 VRA districts.

I actually do understand not wanting to go to Pontiac, but IMO it's not too different from going to Romulus, which will probably happen if you keep both seats in Wayne County.

I'm quite agnostic about going into Southfield. It makes sense from a demographic point of view. Yet it still goes over a county line and you may have to make up for that at another point of the map.

But all seats on the map have to be seen together. The nicest Wayne/Oakland/Macomb layout can force an ugly non-compact remainder seat snaking from Monroe westwards and the separation of Kalamazoo and Battle Creek and then few is gained overall.

[palandio]

Ok, here's my counterproposal. Fairly similar to my earlier map, but with a more compact Detroit area. Not in love with the boundary between the 1st and 2nd but not sure of the best way to improve it.


Sorry for the absence of images, not able to screenshot presently.

So 1, 2 and 10 seem to be solid R.
The 8th despite a clear swing towards the Democrats seems to still have been about Trump +10 in 2020.
The 6th actually seems to be quite competitive at Trump +3 or +4.
The 3rd and 4th seem to have gone to Trump by less than a point.
The 13th seems to have voted for Biden, but only by a point or so.
The 5th seems to have voted for Biden by 2 or 3 points, although it is more Democratic down-ballot.
The 9th is at ca. Biden +9, I would think.
The 7th is at ca. Biden +12 which shows how Ann Arbor can color every seat (Atlas) red.
The 11th and 12nd are of course solid D.

Altogether the map has an R tilt compared to the state's overall political lean. But that R tilt is difficult to avoid given its geography and given these circumstances the map's R tilt is actually very slight.

[palandio]

As I stated before, all seats have to be seen together and most Ann Arbor seats will be not ideal from a CoI point of view, so there has to be a discount for that.

The Lansing-Kalamazoo district looks like a deliberate choice that can be justified by "pairing two mid-sized metros with an orientation towards science and education" or something like that. It's not perfectly compact and gives vibes of partisan linedrawing but altogether it's probably defensible.

The Jackson-Southern Wayne district needs a very good explanation. What CoI is that seat supposed to represent? It's not particularly compact either if you define compactness by minimizing distances between people in the same district.

As is said every map will have its weak points and these can be weighed up if the rest of the map is particularly nice, but I wanted to point out where explanation would be needed, particularly when explicitly drawing a "CoI-driven" map.

[palandio]

The Lansing-Kalamazoo district looks like a deliberate choice that can be justified by "pairing two mid-sized metros with an orientation towards science and education" or something like that. It's not perfectly compact and gives vibes of partisan linedrawing but altogether it's probably defensible.

The Jackson-Southern Wayne district needs a very good explanation. What CoI is that seat supposed to represent? It's not particularly compact either if you define compactness by minimizing distances between people in the same district.

To understand how this map turned out, you have to consider where I started. I initially drew the Flint-Saginaw-Bay City and Thumb-Exurban Detroit seats. After slotting in the Oakland, Macomb, and Detroit seats, Downriver Wayne and Monroe had an annoying population that wouldn't pair with Washtenaw without an annoying split, caused by my choice to put Southfield in with Detroit to push both VRA seats above 45% AA. Thus, I chose to pair it with Jackson and some rurals to avoid splitting up a natural Ann Arbor COI, even though there's not much inherently linking the two areas.

As for Lansing and Kalamazoo, it's pretty simple. I didn't want to split the Grand Rapids and Southwest Michigan COIs so the only option without splitting Lansing and/or Kalamazoo-Battle Creek (a no-go in my opinion) was to pair the two.

I also think pairing Ann Arbor with Livingston and outer Oakland is probably the best choice from a COI perspective, so I'm happy with how that turned out.

Yes, the problem is quite clear after all:

You start by creating the Flint-Saginaw-Bay City district, which blocks any possibility to shift around seats north of Livingston/Oakland.
St. Clair + Lapeer + Tuscola + Sanilac + Huron is slightly less than half a district quota (0.488 to be precise).
Wayne + Oakland + Macomb is 5.067 quotas, if you add Livingston, Washtenaw and Monroe you arrive at 5.986 quotas which is quite good. If you then add the Thumb you get 6.474 quotas and that's the problem. The best solution could be to take out Washtenaw (0.478 quotas) because then you're left with 5.996 quotas which is near perfection and Washtenaw would be difficult CoI-wise anyways.

Or you have the balls to do this and draw a Flint-Saginaw-Bay City district and a Huron Shore district that doesn't go to far into metro Detroit:

[palandio]

The best thing to do regarding partisan data is to use a Markov Chain Monte Carlo simulation and just make sure the map lies within the middle 33% of all maps IMO. That way no communities have to be broken up while you can still follow the law. Colorado did at least listen to this idea late in the commission. Probably too late for that by now though. I guess you would also have to program the simulation to draw 2 45% black seats.

How would that MCMC work? You start with an initial map, possibly the one you want to evaluate and then step by step you propose random incremental changes that are accepted as long as certain measures (regarding e.g. compactness, integrity of administrative divisions, agglomerations, etc.) remain good enough (i.e. at least as good as the initial map). Then after some time you get a distribution of maps.

That all sounds good, but how do you choose the incremental changes? How do you make sure that the space of all admissible plans is contiguous?

In spring I came up with a metric and an optimization algorithm https://talkelections.org/FORUM/index.php?topic=432371.0 based on a simulated annealing-like method that converged by default on a (not necessarily optimal) map. The result could be different between runs. In the case of Michigan the result was very clear: If I lowered the energy slowly enough, the fundamental layout was always the same (The MI maps posted on the old thread are from an earlier version of the program where I didn't use census tract like I used later, but the result is very similar):

1 North (Safe R)
2 West (Safe R)
3 Kent Co. and ca. two smaller counties in its East/SE (Tossup)
4 Tri-Cities and Huron Bay (Safe R)
5 Flint to Port Huron (Likely to Safe R) [pairing of Flint with Saginaw or the Tri-Cities sadly never remained stable]
6 SW, including Kalamazoo, Battle Creek, Berrien Co. (Lean R)
7 Lansing and Jackson (Tossup)
8 De-packed Ann Arbor, including Monroe Co. and most of Livingston Co. (Safe D)
9 Outer Oakland Co. (Tossup, but trending D)
10 Macomb Co. (Nowadays likely R)
11 Outer Wayne Co. (Likely D)
12, 13 Inner Wayne and Inner Oakland (both Safe D), would have to be reordered to be VRA-compliant

[palandio]

(Bumping a very old thread - I know, I'm sorry!)

Competitive map I came up with for MI:  https://davesredistricting.org/maps#viewmap::10f6b431-05bf-43fa-ad0d-3ec99eddd423. 3 Safe R seats, 3 Safe D seats, and 7 (yes, 7) very competitive seats (the election I used was the 2020 presidential race). Just quickly skimming through their 2020 and 2016 presidential voting (plus the 2020 Senate race to compare where Biden over and unperformed Peters):

District: 2020-PRES, 2020-SEN (2016-PRES)
1: Biden+2.2; James+3.3 (Trump+5.3)
2: Trump+3.5; James+8.6 (Trump+9.0)
3: Trump+22.3; James+24.2 (Trump+24.1)
4: Biden+0.4; James+0.5 (Trump+2.0)
5: Trump+21.5; James+20.8 (Trump+24.6)
6: Biden+1.0; Peters+3.2 (Clinton+0.8)
7: Trump+26.3; James+24.5 (Trump+27.8)
8: Biden+1.1; James+1.0 (Trump+4.7)
9: Trump+0.1; Peters+1.5 (Trump+4.4)
10: Biden+2.4; Peters+1.1 (Clinton+0.5)
11: Biden+30.0; Peters+26.9 (Clinton+25.4)
12: Biden+15.9; Peters+16.9 (Clinton+11.9)
13: Biden+77.9; Peters+75.6 (Clinton+80.1)

Biden (D) won 8 districts in 2020; Trump (R) won 5.
James (R) won 7 districts in 2020; Peters (D) won 6.
Trump won 8 districts in 2020; Clinton (D) won 5.
And, surprising me, even Gretchen Whitmer (D) only won 8 districts in 2018. I'd have guessed she won 9 or perhaps even 10 (with 10 probably being a stretch).

You can see that generally, in Western MI, Biden did noticeably better than Gary Peters and Hillary Clinton, whereas in Eastern MI, there wasn't much of a difference. While Peters ran behind Biden throughout Western/Southwestern MI, in the eastern portion of the state, he tended to do better than Biden (in certain districts, at least - including the state's lone Peters/Trump district). And, of course, while Biden did much better than Clinton throughout suburban Southwest MI, in rural and urban MI, either Clinton did better than Biden, or Biden did only a little better than Clinton.

One novelty here IMO is MI08 and MI09. These are two seemingly very similar, purple districts in the Macomb/Oakland County area. However, interestingly, the 8th is a Biden-James district (Biden+1.1; James+1.0) while the 9th is the opposite - a Trump-Peters district (Trump+0.1; Peters+1.5)! I wonder why this is the case. (Of course, both the 8th and the 9th voted for Trump in 2016.)

The thing about Michigan is that several highly competitive districts are basically default (e.g. Lansing, Grand Rapids), others are not inevitable, but easy to draw (Flint-Saginaw and two districts in Macomb and Oakland). Some are a bit of a stretch (from Kalamazoo to its West, from Outer Wayne County to its South) and some seem artificial (pairing Ann Arbor with rurals). But the main challenge is to get them all on one map.

The following map is based on the new congressional map (which has its issues, of course) and doesn't rely on major district contortionism. The biggest change is in the area of the 5th and 6th. Apart from that it's mostly some tweaking around to get the districts fully competitive. And it's just a quick sketch.
https://davesredistricting.org/join/869ca613-10ce-4f8d-bda9-c1963b1331ac