US House Redistricting: Iowa

[EastAnglianLefty]

Though the legislative maps seem to have a particularly high number of county splits. Is that because of very strict rules on population equality?

[jimrtex]

Though the legislative maps seem to have a particularly high number of county splits. Is that because of very strict rules on population equality?

Yes, plus nesting rules, and the number of districts.

The actual range for 2010 Senate districts is -0.75% to +0.90%. Standard deviation is 0.44%, so they may have rejected a few over 1% deviation.

Senate districts nest within congressional districts (to the extent possible). House districts nest within senate districts.

There are 50 senate districts. When Iowa had 5 congressional districts, each had 10 senate districts. With 4 congressional districts, there are 12.5 senate districts in each.

One senate district is shared between IA-1 and IA-4; and one between IA-2 and IA-3. Two house districts nest within each senate district. The senate district (SD-26) that spans the IA-1/IA-4 boundary is along the IA-1 panhandle. HD-52 is in the panhandle (and in IA-1), and HD-51 is to the south.

The phenomena that permit whole-county congressional districts break down at the legislative district level.

Iowa has a large number of counties (99) and they are mostly square. You can build relatively good looking structures with a set of similar building blocks. A four-year old can probably do it.

The population is homogeneously heterogeneous. Polk is only about 2/3 the size of a congressional district, and the larger counties are relatively dispersed. This means that it is possible to draw districts with fairly large numbers of counties. The current districts have (20, 24, 16, and 39 counties). Even the district with Des Moines stretches to Nebraska.

Imagine that if you quartered the state into roughly 5x5 county areas. And let's say at each row, you could advance one county, hold the line, or retreat one county. You could do this for five rows. That is 3⁵ or 243 choices. Pick the one with the smallest deviation. But you can do this in two dimensions, for all four district boundaries. 3²⁰. 3.5 billion is a lot of choices even when you have to equalize all four districts.

The quota for senate districts is 60,927. That is smaller than 10 counties, which must be split, and five of those are entitled to more than 2 districts. With 21 whole districts, let's assume that we can finish up four others spanning Scott-Dubuque, Linn-Johnson, Polk-Story, and Polk-Dallas lines. And then a district for the isolated counties of Black Hawk, Woodbury and Pottawatamie. That is a total of 28 districts for at least 13 counties. The other 22 districts are split between 86 counties or about four counties each. It is a lot harder to assemble four counties in groups that match a target population, and even harder in the east.

Alternatively, we are dividing 20, 24, 16, and 39 counties into 12.5 parts each (where the 1/2 part has to be exactly half the size of a full part).

Then you have to divide those senate districts into two house districts. There are four whole-county senate districts (SD-1, SD-4, SD-12, SD-38). All split a county in making the two house districts equal.

It would be better if there weren't nesting. Let's make the senate 47 members and the house 103 members, both prime, and keeping the legislature at 150 total. Then ignore nesting entirely and permit 5% deviation. I think there would be many more whole-county districts.

[Sol]

Here's a potential 2020 map:



IA-01 and IA-02 are tossups pretty much, while IA-03 and IA-04 are safe D and R respectively.

[Hope For A New Era]

Here's a potential 2020 map:



IA-01 and IA-02 are tossups pretty much, while IA-03 and IA-04 are safe D and R respectively.

So in terms of net effect it would just be switching the Safe D district from 2 to 3. I guess that's fine. I think Loebsack and Finkenauer would be relatively safe for a while in this map. They both seem to be popular and are pretty good fits for their districts.

Iowa is interesting because it seems to be the only place where the "population tilting" of the Midwest (east is flat or losing population, west is flat or gaining population) is working in reverse. Western Iowa is emptying out fast, Eastern Iowa is doing just fine.

[DINGO Joe]

Here's a potential 2020 map:



IA-01 and IA-02 are tossups pretty much, while IA-03 and IA-04 are safe D and R respectively.

So in terms of net effect it would just be switching the Safe D district from 2 to 3. I guess that's fine. I think Loebsack and Finkenauer would be relatively safe for a while in this map. They both seem to be popular and are pretty good fits for their districts.

Iowa is interesting because it seems to be the only place where the "population tilting" of the Midwest (east is flat or losing population, west is flat or gaining population) is working in reverse. Western Iowa is emptying out fast, Eastern Iowa is doing just fine.

At least based on Census estimates, 3 is still too big, maybe drop Jasper.  As for population growth in the state it's not so much regional as it is Metro Des Moines and Metro Cedar Rapids-Iowa City growing while rural Iowa declines and smaller cities are relatively flat.

[Sol]

Here's a potential 2020 map:



IA-01 and IA-02 are tossups pretty much, while IA-03 and IA-04 are safe D and R respectively.

So in terms of net effect it would just be switching the Safe D district from 2 to 3. I guess that's fine. I think Loebsack and Finkenauer would be relatively safe for a while in this map. They both seem to be popular and are pretty good fits for their districts.

Iowa is interesting because it seems to be the only place where the "population tilting" of the Midwest (east is flat or losing population, west is flat or gaining population) is working in reverse. Western Iowa is emptying out fast, Eastern Iowa is doing just fine.

At least based on Census estimates, 3 is still too big, maybe drop Jasper.  As for population growth in the state it's not so much regional as it is Metro Des Moines and Metro Cedar Rapids-Iowa City growing while rural Iowa declines and smaller cities are relatively flat.

FWIW, that map was done on 2018 estimates--it'll obviously require revising once this census is actually done but it should be pretty close.

[lfromnj]

As the Iowa GOP has expanded their majorities in both chambers there is a good chance they could ignore the commission .







They can either go for a 4-0 map or a 3-1 map if they chose too. The GOP could probably sweep a 4-0 map in a Biden midterm although 3-1 just make everyone happier and 4-0 would probably go badly just like a pure 3-0 in NM could go a bit badly.

[Idaho Conservative]

As the Iowa GOP has expanded their majorities in both chambers there is a good chance they could ignore the commission .







They can either go for a 4-0 map or a 3-1 map if they chose too. The GOP could probably sweep a 4-0 map in a Biden midterm although 3-1 just make everyone happier and 4-0 would probably go badly just like a pure 3-0 in NM could go a bit badly.

numbers in those?

[lfromnj]

As the Iowa GOP has expanded their majorities in both chambers there is a good chance they could ignore the commission .







They can either go for a 4-0 map or a 3-1 map if they chose too. The GOP could probably sweep a 4-0 map in a Biden midterm although 3-1 just make everyone happier and 4-0 would probably go badly just like a pure 3-0 in NM could go a bit badly.

numbers in those?

Trump +15 each for first and Trump +6 is the closest in the  2nd map.

[Idaho Conservative]

As the Iowa GOP has expanded their majorities in both chambers there is a good chance they could ignore the commission .







They can either go for a 4-0 map or a 3-1 map if they chose too. The GOP could probably sweep a 4-0 map in a Biden midterm although 3-1 just make everyone happier and 4-0 would probably go badly just like a pure 3-0 in NM could go a bit badly.

numbers in those?

Trump +15 each for first and Trump +6 is the closest in the  2nd map.

3-1 is probably a good idea tbh.  Or maybe 1R-2LR-1LD

[America Needs a 13-6 Progressive SCOTUS]

Here are 2 possible nonpartisan map configurations:

[Torie]

At Red Racing Horses, they are now busy working at fantasizing on a Pub gerrymander of all places - Iowa! I suggested to the boys that to stay out of trouble they should focus on gerrymandering Vermont.

[muon2]

As the Iowa GOP has expanded their majorities in both chambers there is a good chance they could ignore the commission .







They can either go for a 4-0 map or a 3-1 map if they chose too. The GOP could probably sweep a 4-0 map in a Biden midterm although 3-1 just make everyone happier and 4-0 would probably go badly just like a pure 3-0 in NM could go a bit badly.

The commission in IA has no real role in redistricting. The body that drafts legislation (LSA) is directed by statute to create redistricting plans according to specific criteria. The legislature can vote plans up or down, but can't amend them. If they reject a plan from the LSA the legislature is required to redirect the LSA as to which factors they need to better address in the next version. If they reject three plans from the LSA the legislature can go on their own, but will have to follow the same statutory criteria. If they don't follow the criteria there is certain to be a court challenge. The current process was put in place in 1980 to avoid regular court challenges to redistricting plans.

[Torie]

I tried to come up with a Pub gerrymander that was in the same universe as what the black box the technocrats use might create. This was about the best I could come up with after about an hour.

[VAR]

Put together a State Senate map:



https://davesredistricting.org/join/3292b655-5664-42a6-9abd-f9433c58b7dd

Seat composition:
2016: 34 Trump — 16 Clinton
2018: 31 Reynolds — 19 Hubbell

[VAR]

State House map:



https://davesredistricting.org/join/777a517a-251c-4e74-a547-5cb37e6b7f14

Seat composition:
2016: 66 Trump — 34 Clinton
2018: 57 Reynolds — 43 Hubbell

[Frodo]

Put together a State Senate map:



https://davesredistricting.org/join/3292b655-5664-42a6-9abd-f9433c58b7dd

Seat composition:
2016: 34 Trump — 16 Clinton
2018: 31 Reynolds — 19 Hubbell

State House map:



https://davesredistricting.org/join/777a517a-251c-4e74-a547-5cb37e6b7f14

Seat composition:
2016: 66 Trump — 34 Clinton
2018: 57 Reynolds — 43 Hubbell

Can you get these maps color-coded for partisan purposes?  I have no doubt I will see a Republican sea of red (or Atlas blue) interspersed with a few tiny Democratic islands, but still.  

[VAR]

Can you get these maps color-coded for partisan purposes?  I have no doubt I will see a Republican sea of red (or Atlas blue) interspersed with a few tiny Democratic islands, but still.  

Sure - here you go. Data from the 2016 presidential election is used for both maps.

House:



Senate:

[Frodo]

Can you get these maps color-coded for partisan purposes?  I have no doubt I will see a Republican sea of red (or Atlas blue) interspersed with a few tiny Democratic islands, but still.  

Sure - here you go. Data from the 2016 presidential election is used for both maps.

House:



Senate:

Thanks!

[Meatball Ron]

Put together a State Senate map:



https://davesredistricting.org/join/3292b655-5664-42a6-9abd-f9433c58b7dd

Seat composition:
2016: 34 Trump — 16 Clinton
2018: 31 Reynolds — 19 Hubbell

State House map:



https://davesredistricting.org/join/777a517a-251c-4e74-a547-5cb37e6b7f14

Seat composition:
2016: 66 Trump — 34 Clinton
2018: 57 Reynolds — 43 Hubbell

Can you get these maps color-coded for partisan purposes?  I have no doubt I will see a Republican sea of red (or Atlas blue) interspersed with a few tiny Democratic islands, but still.  

Are these meant to be Republican gerrymanders, or is it just the nature of geography in Iowa that Dems will win a much lower % of the seats than their PV performance reflects? Specifically looking at the share of Hubbell seats relative to his ~48% share of the popular vote.

[lfromnj]

Put together a State Senate map:



https://davesredistricting.org/join/3292b655-5664-42a6-9abd-f9433c58b7dd

Seat composition:
2016: 34 Trump — 16 Clinton
2018: 31 Reynolds — 19 Hubbell

State House map:



https://davesredistricting.org/join/777a517a-251c-4e74-a547-5cb37e6b7f14

Seat composition:
2016: 66 Trump — 34 Clinton
2018: 57 Reynolds — 43 Hubbell

Can you get these maps color-coded for partisan purposes?  I have no doubt I will see a Republican sea of red (or Atlas blue) interspersed with a few tiny Democratic islands, but still.  

Are these meant to be Republican gerrymanders, or is it just the nature of geography in Iowa that Dems will win a much lower % of the seats than their PV performance reflects? Specifically looking at the share of Hubbell seats relative to his ~48% share of the popular vote.

The latter. The current map is fairly similar in the number of Clinton districts.

[President Punxsutawney Phil]

So is it possible to make a State Senate map and a State House map where the median seat voted for Reynolds by the same margin as the state as whole and Hubbell won a percentage of seats equal to his statewide vote share? Bonus points if county splits are kept to the minimum necessary.
Also: does the geography get better for Ds or worse when the districts get bigger?

[lfromnj]

So is it possible to make a State Senate map and a State House map where the median seat voted for Reynolds by the same margin as the state as whole and Hubbell won a percentage of seats equal to his statewide vote share? Bonus points if county splits are kept to the minimum necessary.
Also: does the geography get better for Ds or worse when the districts get bigger?

better clearly as the median district goes to like 5 points left of the state.

[Thunder98 🇮🇱 🤝 🇵🇸]

Made a 3-1 R map, though 3 districts are completive.


https://davesredistricting.org/join/88897bc0-abf0-46a4-8f5f-46cec99b5c7e

[Meatball Ron]

Made a 3-1 R map, though 3 districts are completive.


https://davesredistricting.org/join/88897bc0-abf0-46a4-8f5f-46cec99b5c7e

This feels appropriate to me. Could be 4R-0D in an R wave, or 3D-1R in a D wave, but the typical outcome will be 3R-1D. Probably the fairest outcome given the state's partisanship and elasticity.