What districts would have Dems won back if not for gerrymandering?

[traininthedistance]

Also, to answer the thread's question:


Would have won back (In some cases, I assume better candidates would have run with more favorable maps):

Ohio 1 (Chabot)
Ohio 6 (Turner)
Ohio 7 (Gibbs)

There's no way the Dems could have unseated Turner without a grotesque gerrymander. He is uniquely popular in the Dayton area for his term as mayor and actually gets a non-negligible amount of votes in inner-city black neighborhoods that vote around 99-0 on the presidential level. He typically performs about 10 points better than the generic Republican in the Dayton area. With a better opponent, he might not overperform quite as much, but there's no way the Dems could take out Turner. You might be able to take the seat after he retires though. That's true of the current map too. Obama won Turner's current seat in 2008.

Chabot would be the easiest target for the Dems in redistricting, but he'd even still have a chance in non-presidential years.

Gibbs would be gone if his seat is turned into an Akron seat (or maybe it would be Renacci's ?), so I'll agree with that one. Gibbs had an awful opponent last fall, but could be in danger with a reasonable opponent. The same can be said for David Joyce.

In a neutral year with a neutral map, I'd say Ohio should probably be expected to have a 10-6 Republican delegation simply from the urban Democratic packing and VRA seat. So I think two seats would be a fair estimate.

The Democrats naturally envision Chabot's seat to be, err, conveniently drawn in a manner of their choosing. The same people who complain about Cincinnati being split into 2 districts will split Cleveland into 2 districts without hesitation. There are plenty of maps as proof.

I believe all cities shouldn't be split unless it is to large to fit in a single district. Cincinnati can easily be put in a single district, as can Dayton, Columbus, Toledo, and Akron. Cleveland is too large for a single district, plus there are VRA concerns.

Eh, Cleveland can fit in one district, actually.  Columbus, OTOH, not so much anymore (especially not with its insane boundaries).  And at this point I'd probably prefer a district that took in all of Cleveland to one which snaked down to Akron as a way of disguising a Republican gerrymander in VRA's clothing.

[traininthedistance]

Eh, Cleveland can fit in one district, actually.  Columbus, OTOH, not so much anymore (especially not with its insane boundaries).  And at this point I'd probably prefer a district that took in all of Cleveland to one which snaked down to Akron as a way of disguising a Republican gerrymander in VRA's clothing.

Interesting. Your own map made the, err, convenient choice of splitting Cleveland, Columbus, and Akron, and not Cincinnati and replicates that so called gerrymandering tactic.


https://uselectionatlas.org/FORUM/index.php?topic=124180.msg3385020#msg3385020

That's not the most recent map I've posted w/r/t Ohio, this is:

https://uselectionatlas.org/FORUM/index.php?topic=173216.msg3723134#msg3723134

You will note that I have changed my mind since, and now would prefer a whole Cleveland.

And, you do realize that: a) splitting Cleveland and Akron like I did is a pro-Republican move, and if it is to be justified, would be justified via the VRA anyway (not an issue in Cincy) and b) Columbus is too large for a district, so you have to split it no matter what (and the municipal boundaries are such that an all-Columbus district is basically impossible). 

I await your retraction. Patiently. 

[traininthedistance]

Hm.  What do people think of this proposal as a way to lessen, if not entirely neutralize, the partisan effects of line-drawing (both from gerrymandering, and "natural packing")?

Districts should be drawn in each state so that half of them have a PVI more D than the state as a whole, and half of them have a PVI that is more R than the state as a whole.  Maybe allow wiggle room of a point or two in either direction.  So, in the case of Michigan, you'd need seven districts D+4 or more Dem, and seven districts that were D+4 or more Pub.  Conversely, a state like North Carolina would be mandated to have six districts that are at least R+3, and a seventh right around that number.

This should safeguard against the worst abuses, in both directions. 

[traininthedistance]

Hm.  What do people think of this proposal as a way to lessen, if not entirely neutralize, the partisan effects of line-drawing (both from gerrymandering, and "natural packing")?

Districts should be drawn in each state so that half of them have a PVI more D than the state as a whole, and half of them have a PVI that is more R than the state as a whole.  Maybe allow wiggle room of a point or two in either direction.  So, in the case of Michigan, you'd need seven districts D+4 or more Dem, and seven districts that were D+4 or more Pub.  Conversely, a state like North Carolina would be mandated to have six districts that are at least R+3, and a seventh right around that number.

This should safeguard against the worst abuses, in both directions. 

I know you want to move towards House representation that more closely reflects the popular vote, but the Pubs are never go to agree to that. In fact, I suspect I, and Muon2 too for that matter, are too partisan to agree to that. What I am willing to do however, if need be, is skew a bit towards an excessive number of swing districts. What the Dems would really want, at a minimum, and I understand that, is to offset the screwing that they get from the VRA. That isn't going to happen either. So we need to do the best we can with what reasonable folks on both sides are willing to do.

I would contend that opposing the idea that House representation should closely represent the popular vote just is, well, unreasonable.

But yes, in the practical world where we live (in which you have apparently indicated there is no such thing as a reasonable Pub ) I would be willing to accept more limited measures to counteract VRA screwage, embedded within an independent, non-partisan framework. 

[traininthedistance]

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New Jersey is rather unique in the US with both strong counties and town subdivisions. In the Midwest, many voters do not know their township but certainly know their county. For most the township exists as a basis for the county to track assessments and to group voting precincts. Only in farm areas where the township is the primary provider of road maintenance does it take a more prominent role.

Pennsylvania is the same; New York is a little more complicated with its "villages" but I believe that NY towns all have some level of government that extends well beyond rural road maintenance.  (I don't know to what extent school districts line up with town boundaries, though: in NJ every muni has its own school district at least on paper, in PA school district lines follow muni boundaries but often include multiple towns).

I worry that, if your proposed guidelines for dealing with metro areas would allow the last map you put up, then they are far too toothless for my taste.  Splitting Livingston from the Detroit area, and the tri-chop of Lansing's core, together have the effect of ensuring that there is no real Lansing district, when other maps have shown how it is easy to make a single whole-county Lansing district that substantially keeps the whole of the core together in one district, rather than sundering it three ways.   I understand your concerns about not wanting what you consider to be "subjective" CoI criteria... but a "foolish consistency is the hobgoblin of little minds", as they say.  

Perhaps a balancing test could be added that keeping small MSA cores in one district, or large MSA cores in one apportionment group, or different parts of a CSA in the same district/group, is a priority goal- and that failure to do so should count as a county cut for the purposes of scoring.  (Maybe breaking off parts of a CSA would be worth half a county cut or something.)

[traininthedistance]

You must be logged in to read this quote.

New Jersey is rather unique in the US with both strong counties and town subdivisions. In the Midwest, many voters do not know their township but certainly know their county. For most the township exists as a basis for the county to track assessments and to group voting precincts. Only in farm areas where the township is the primary provider of road maintenance does it take a more prominent role.

Pennsylvania is the same; New York is a little more complicated with its "villages" but I believe that NY towns all have some level of government that extends well beyond rural road maintenance.  (I don't know to what extent school districts line up with town boundaries, though: in NJ every muni has its own school district at least on paper, in PA school district lines follow muni boundaries but often include multiple towns).

I worry that, if your proposed guidelines for dealing with metro areas would allow the last map you put up, then they are far too toothless for my taste.  Splitting Livingston from the Detroit area, and the tri-chop of Lansing's core, together have the effect of ensuring that there is no real Lansing district, when other maps have shown how it is easy to make a single whole-county Lansing district that substantially keeps the whole of the core together in one district, rather than sundering it three ways.   I understand your concerns about not wanting what you consider to be "subjective" CoI criteria... but a "foolish consistency is the hobgoblin of little minds", as they say.  

Perhaps a balancing test could be added that keeping small MSA cores in one district, or large MSA cores in one apportionment group, or different parts of a CSA in the same district/group, is a priority goal- and that failure to do so should count as a county cut for the purposes of scoring.  (Maybe breaking off parts of a CSA would be worth half a county cut or something.)

The purpose of my scoring is not to find a single winning entry. Mathematically that is not a tractable problem given the large number of census blocks (or even voting districts). The purpose is to find an objective set of plans that can then be made subject to the review by a group of humans who would select from the set. Subjectivity is fine for that review, but if subjectivity gets a hold on the creation of a set all sorts of games become possible. The core rules are thus immune to exceptions, and that is left to the reviewers to apply.

I would prefer not to put up any metro rules because as one goes through the states there are inevitable exceptions. If you don't like my Lansing chop offering that's fine. My point is that if one looks at each district on its own, there may be no reason to exclude it from the set that goes to the reviewers. Neither the shape of that CD 4 not the way it selects some of the whole municipalities to include from Ingham is particularly unusual. It's only when viewed in the context of the the neighboring districts and the global knowledge that other maps don't split the metro that it becomes objectionable. I claim that that is exactly why a human element is part of the process.

Yeah, I get what you're saying here.  I guess I would then just hope that the core rules allow just a little bit of leniency w/r/t county chops, so that other maps which do a better job of keeping metros together at the expense of a chop or two (obviously within some limit that could perhaps be set in stone) could get to the final round, as it were.

[traininthedistance]

Ladies and gentlemen, the perfect Pennsylvania.  (Using a max 0.5% deviation, that is.)



Only six counties have any chops at all, and five districts are whole-county.  Only Philly is split, and it is only split along ward boundaries.  District 2 is 59% black, District 1 is minority-plurality by total population (though white majority by VAP, as a result of how the ward math worked out; would've rather had it min-maj total, which is almost certainly possible if you get ugly and abandon that nice Broad St. boundary).



In addition, metro areas are kept as damn near pristine as possible.  In SEPA, the five-county Delaware Valley plus Reading (part of the Philly CSA) plus Lancaster (its own metro, not part of any CSA) is one apportionment district.  In addition, the three inner suburban counties, Reading, and Lancaster, are all min split- there is an all-Montgomery district, and Delaware/Bucks/Lancaster/Reading are all kept whole.  The extra chops (all of which I'm pretty sure are necessary) are confined to Chester and Philly.

The 12 (old 19)-17-15 apportionment district in Central PA and the Lehigh Valley does the worst in terms of metro contiguity.  The three counties of the Allentown metro are just a wee bit too large, so a chop of about 5K from Carbon is given to 17.  Not technically a microchop, but it's in that spirit.  The Harrisburg area fares worst, as there are three districts in the MSA, and Cumberland is chopped.  But at least the core-Dauphin- is whole, and Perry County is outlying and rural, and the York-Adams-Carlisle district can't avoid a chop.

In SWPA, the Pittsburgh-New Castle CSA is almost perfectly in 2 districts, except for the addition of Greene in the far southwest corner (it's surrounded) and the subtraction of Westmoreland.

The only other instance of MSAs being broken up is that Wyoming County is separated from the rest of the Scranton-Wilkes-Barre MSA. But, again, it's an outlying county, and Monroe-Lackawanna-Luzerne is just too perfect.  You'd have to split something there, and if it's not what I did, it would be a different MSA plus a county.  Worth it, easy.  As for CSAs, the Lock Haven micro is split from the Williamsport metro; an earlier draft had them together in 10 but splitting them allowed 9 and 12  to no longer be underpopulated, and to be whole-county.  So it saved two cuts, again.

I think this is a map that would be hard to improve upon.  You could arguably clean up things between 10 and 17 at the expense of a county cut if you wanted to, that's about it.  And of course the lines within Allegheny County will always remain gameable for partisan advantage.

[traininthedistance]

As they say - great minds think alike.

Here's a version incorporating Verily's suggestions for western PA. I've also made some adjustments to SE PA.  I still like to rely on whole counties, since that is one of the defensible criteria to allow deviations in excess of one person. CoI is a nebulous criteria and exact population equality would generally be needed.

Here were my criteria and their impact on the map:

Districts are drawn to use whole counties to the extent possible and counties larger than one district have as many whole districts within as possible. The map divides three counties other than the ones that have whole districts within. Within counties no city or township is divided. Within Philly no ward is divided.

Instead of limiting the deviation, I limited the range from the smallest to largest district to be less than 1%. This is from SCOTUS decisions, and note that a 0.5% deviation limit results in a 1% range limit. The population range here is less than 1% (-0.7% to +0.3%) and the mean deviation is 884 persons.

CD 2 is designed to comply with the VRA and is 61.8% BVAP. CD 1 keeps the Hispanic wards together and is 18.8% HVAP and 18.2% BVAP. CD 1 also includes Chinatown and the Asian areas of S Philly with 7.6% AVAP.

Other than the changes in central PA, which have the effect of relocating my chop in Cambria to one in Cumberland, and the shape of the Pittsburgh CD, I can't see much to complain about.

I didn't even remember that map- yeah, it makes sense we'd converge on roughly the same thing.  Your central PA is, I think, better (same amount of chops, but having the entire Harrisburg MSA in one district, as well as putting Williamsport-Lock Haven together, are both preferable).  Though I'm guessing you had to go past the strict 0.5% limit to make it happen.

[traininthedistance]

By splitting Scranton from Wilkes-Barre the erosity can be greatly reduced for CD 10.

Yeah, this is where I say that "cutting down on erosity above all" can lead to rotten outcomes.  Scranton and Wilkes-Barre need to be in the same district, and if that increases erosity then so be it.  There are worse things than a little erosity.

I'm not necessarily opposed to adding a chop to the western side of 10 to clean it up... but districts 11 and 15 in my map and muon's old map are obviously optimal, and anything that goes away from that is a step backwards.

[traininthedistance]

You'd have to gerrymander Allegheny to move the needle there - swapping CD 18 up along the east side of Pittsburgh moves it to R+1, so it would move the skew by 1.

So, basically, this:

?

Though it must be noted that having 18 take all of the Mon Valley is a decision justifiable on more than just skew-reducing grounds, though skew reduction is certainly sufficient reason to draw it that way.

Let it be known that even my PA map was Pub-favoring.  (I guess my district 17 is marginally more competitive as well, but that still doesn't get us to parity.)

[traininthedistance]

Hm.  What do people think of this proposal as a way to lessen, if not entirely neutralize, the partisan effects of line-drawing (both from gerrymandering, and "natural packing")?

Districts should be drawn in each state so that half of them have a PVI more D than the state as a whole, and half of them have a PVI that is more R than the state as a whole.  Maybe allow wiggle room of a point or two in either direction.  So, in the case of Michigan, you'd need seven districts D+4 or more Dem, and seven districts that were D+4 or more Pub.  Conversely, a state like North Carolina would be mandated to have six districts that are at least R+3, and a seventh right around that number.

This should safeguard against the worst abuses, in both directions. 

For the record, the enacted New Jersey map complies with this criteria.

Yet, of course, this poster in question doesn't like the New Jersey map and wants to blow Republican districts up.

Link


Curious.

Well, how does the NJ map score on muon's (more robust) skew measure?   Is it even on that front, too?  I think you know what the answer would be.

How about we enact a new Pennsylvania map that complies with my proposed criteria (which is, mind you, supposed to be a fail-safe against the most egregious of partisan effects, and not a sufficient marker of good redistricting by itself) and then I'll stop complaining about NJ.  That's more than fair.

[traininthedistance]

Of course I briefly searched through this thread for the specific muon2 criteria that you hint about. Then again you tossed your own criteria aside in a half second when you decided it didn't achieve your hack partisan outcome, so I suspect you'll do his as well.

Please quote where, exactly, I "tossed aside" the usage of muon's skew criteria.  What I disagreed with is the idea of only using county chops/erosity as methods for scoring districts without regard to skew or metro contiguity, which appears to me rather more like the opposite of what you are claiming.

By this standard, the enacted NJ map has 6D, 2e, 2r, 2R.

Actually it is 6D, 2e, 1r, 3R.  Check your PVIs again.  Of course, looking at it more holistically, the lack of any districts at all in the "lean D" range is a good tipoff that what we are looking at is in reality a partisan gerrymander.  But you're a smart guy, I'm sure you knew that, even if you will never admit as such.

[traininthedistance]

Thank you. I was following your lines for the balance of the map with which I was satisfied. Yes, your lines losing the chop are superior. I just took your chops from CD's with which I did not mess as holy writ. I guess that was a mistake.

I'm just trying to strike the right balance between your push to minimize erosity and train's desire to minimize chops. My adjustment is merely to refine the balance. As my optometrist would say "Is it better with lens 1 or 2?"

I would say that my hobbyhorse is more MSA/CSA (and muni) chops than county chops; I think that my desire to minimize county chops is not really any more strong than yours or Torie's (though it obviously does exist as well).

[traininthedistance]

Thank you. I was following your lines for the balance of the map with which I was satisfied. Yes, your lines losing the chop are superior. I just took your chops from CD's with which I did not mess as holy writ. I guess that was a mistake.

I'm just trying to strike the right balance between your push to minimize erosity and train's desire to minimize chops. My adjustment is merely to refine the balance. As my optometrist would say "Is it better with lens 1 or 2?"

I would say that my hobbyhorse is more MSA/CSA (and muni) chops than county chops; I think that my desire to minimize county chops is not really any more strong than yours or Torie's (though it obviously does exist as well).

Fair enough. Next question (for Torie, too) - is it worth a chop to reduce polarization and/or skew?

My first instinct is to say "yes to reduce skew, no to reduce polarization".  But, within limits and with exceptions.  I would actually say that, when it comes to polarization, it depends on the state.  The more elastic a state is, or the more naturally swingy area there is, the more I'd be amenable to polarization-reducing chops.  Ideally, the more a county chop can serve multiple purposes (by, say, pushing the overall skew down while also keeping the core of an MSA together), the more I consider it a worthwhile chop.

[traininthedistance]

Here by the way is a map of Maryland that a drew a couple of weeks ago, which restores to the Pubs the 2 CD's that the Dems ripped off in their gerrymander. I just thought I would throw it on the pile.



And here is an alternative iteration, with perhaps a tad less erosity. It is not applicable here, but this is one instance where which map I would prefer would turn on which reduced polarization the most. In MD, good redistricting principles basically shut out competitive districts, and to reach for them, would just be a bridge too far. So it just doesn't matter here.

Well, at the very least Cecil County is normally considered to be part of the Eastern Shore, so it should really go in 1 instead of Anne Arundel.  And a 5-3 map is, if anything, gerrymandered towards the Pubs given that Maryland is just so Democratic overall.  I haven't done the exact skew calculations but I would expect 6-2 to be the "fair" expected result given the state's partisan lean.

How about something like this:



If anything, this map is still Pub-leaning, since the Dems are still only clearly favored in five of the districts.  District 3, taking in Howard and the vast majority of Anne Arundel, is both a swing district (53.9% Obama, so a PVI of D+1 maybe? ) and entirely consistent with any sort of good redistricting principle you'd care to cite.  So you should be happy with it.

[traininthedistance]

Train's map of MD adds a lot of additional erosity for no doubt partisan reasons.

What additional erosity?  No, seriously, you're imagining things here.  I don't see it at. all.  Keep in mind that Cecil has to go into 1- I'm not going to let you get away with splitting the Eastern Shore for partisan gain, dude.  My map is a zillion times more sensible than that abomination that is your District 1.

And I would absolutely draw Massachusetts in such a way as to give the Pubs at least one district they'd have a real shot at.

[traininthedistance]

Train's map of MD adds a lot of additional erosity for no doubt partisan reasons.

What additional erosity?  No, seriously, you're imagining things here.  I don't see it at. all.  

And I would absolutely draw Massachusetts in such a way as to give the Pubs at least one district they'd have a real shot at.

I guess Muon2 can help us on the erosity issue for MD, on which we disagree. We just have a fundamentally different philosophy here Train, and such is life. We will just have to agree to disagree, because we are both stubborn cusses on this, and I don't think it possible to close the gap. That happens sometimes. Moving stuff around for partisan reasons to me is perhaps not quite as fraught with peril as this communities of interest scam, but it has the potential for great mischief, and gaming.

So, you can't defend splitting Cecil from the rest of the Eastern Shore, or explain how my map is unacceptably erose whereas yours is peachy.  Gotcha.

[traininthedistance]

Train's map of MD adds a lot of additional erosity for no doubt partisan reasons.

What additional erosity?  No, seriously, you're imagining things here.  I don't see it at. all.  

And I would absolutely draw Massachusetts in such a way as to give the Pubs at least one district they'd have a real shot at.

I guess Muon2 can help us on the erosity issue for MD, on which we disagree. We just have a fundamentally different philosophy here Train, and such is life. We will just have to agree to disagree, because we are both stubborn cusses on this, and I don't think it possible to close the gap. That happens sometimes. Moving stuff around for partisan reasons to me is perhaps not quite as fraught with peril as this communities of interest scam, but it has the potential for great mischief, and gaming.

So, you can't defend splitting Cecil from the rest of the Eastern Shore, or explain how my map is unacceptably erose whereas yours is peachy.  Gotcha.

I said let Muon2 opine on the erosity issue, so we don't have to continually bite at each other on that one. I thought about Cecil when I drew the map, but it was just too far north, and added too much erosity, and the bay turns into but a river there anyway (your comment sounds more like a COI issue anyway - the important thing is that bridge connection to Annapoplis). It also makes the NE corner CD compact, along with making the Eastern shore CD more compact. That is why I did it. I didn't even look at the partisan numbers until I was done, and doubt the Cecil issue per se is that important to partisan issues anyway. I guess I just can't persuade you that I don't have ulterior motives, so there is no point anymore in even discussing that I guess. Thanks.

I... still don't see how adding Cecil adds erosity?  Just asserting as such doesn't make it so?  It seems to me that your issue here, perhaps, is that you are overly wedded to lines that run straight north-south and east-west even when the natural geography of a state is geared towards diagonals.  This seems to me the one possible gloss of your horreur at my eminently fair and compact map which does not require ulterior motives to come into play.

And I have been very careful to try and not assume ulterior motives, as well as play along as best I can with your throw-the-baby-out-with-the-bathwater school of thought on CoI.  (Some things, of course, are just too obvious to let slide, like the Eastern Shore.  And I will not stop harping on MSAs.  But in general I have bent over backwards to accept your terms of the debate, even though I could very easily, and possibly should, challenge some of them.)  But, of course, it is hard when you seem to refuse to do the same.  Perhaps maybe you could refrain from assuming that my proposals are made with partisan intent, and then I would be more than happy to do the same with yours.

[traininthedistance]

Oh, yeah, Massachusetts.  Here's a map that the Pubs here should like.



The purple district is 50.8% Obama, and Romney probably won it.  The Republicans would probably be favored here.  As a competitive bonus, the yellow district is only 56.1% Obama, so not secure for the Dems either.

I did not check closely to see how well the districts lined up with NECTA boundaries, so I'd like to do that with any final Massachusetts map.  I expect that the Springfield NECTA must be split down the middle in any case, which makes me quite sad given my usual priorities.  But, yes, I do think that a fair map in the Bay State would try to give the Pubs a district they could win, and this seems like the easiest way to do so at first blush.

[traininthedistance]

and doubt the Cecil issue per se is that important to partisan issues anyway.

Well, yes.  My concerns are not nearly as partisan as you imagine them to be. 

[traininthedistance]

I'll get to erosity in a different post, but let me clear up what seems an inconsistency on Cecil. Historically Cecil was counted with the Eastern Shore because it sits across the Susquehanna. That history has little to do with the bulk of the population. For over a decade it has been part of the Philly MSA, the Wilmington metropolitan division to be more specific. It's not even outlying, but considered to be a central county in the MSA. Sticking with MSAs, there is no reason to favor its placement on the Eastern Shore any more than putting Anne Arundel there because of the bridge.

And speaking about that bridge, the Baltimore MSA now includes Queen Anne's county on the ES as a central county! Carroll and Harford are the outlying counties. Commuters are now such a significant portion of the population using the bridge that they have overrun the historical population. Even a decade ago when I spent some time on the ES I could see evidence of the transition, particularly where the people live on the peninsula that includes the bridge. So if MSA preservation is a criteria, one cannot ignore that anymore than one can ignore Lackawanna-Luzerne can one? Redistricting is about current populations not historical ones.

One other connection issue concerns the southern end of the Chesapeake. In discussions about WA it was generally agreed that regular scheduled ferry service could replace a public highway for the purposes of determining a connection. The Smith Island ferry links St Marys and Somerset counties. Erosity doesn't care about the bay when links are present. Yet using that link can provide additional options to preserve the aforementioned Queen Anne's link to the mainland. Then again it may not apply since the schedule doesn't show for the winter. However the boats provide a number to call for service even in the winter, so this one is a bit gray.

I noticed that Queen Anne's was part of the Baltimore MSA, but it strikes me as deeply weird that it would be a central county while Harford is considered outlying.  (I'd expect Carroll to be outlying, though.)  I guess if the old native population is that small, and center vs. outlying only takes commuting patterns into account, then I can see how they'd come to that conclusion.  I've been working off the assumption that "central" MSA counties could be more defined by contiguous urbanized area, which strikes me as more intuitive if not necessarily easier to quantify.

In any case, it seems to me that the Eastern Shore district is going to have to take in Baltimore Metro area no matter what, in addition to Queen Anne's.  If metro areas matter, the fact that Cecil is in the Philly metro is all the more reason to make sure it stays with the rest of the Eastern Shore, so the Baltimore burbs district stays within the MSA; if straight lines matter, adding Harford gets you closer to straight lines (with just a small salient of 27K to add) than a large bulge into Anne Arundel; if road connectivity matters, there are three bridges over the Susquehanna between Cecil and Harford compared to just the Bay Bridge to Anne Arundel.  I really find it hard to believe that my District 1 would be objectionable to anybody (the others, we can talk about, I'm all ears).

I'm undecided on the merits of counting ferry links in general (except obviously in places like WA, where they are necessary).  My instinct is that they could technically count but their use should be discouraged, and not count "as well" as major road or rail links.  Opening ferries up to map-drawers immediately makes a Staten Island-Lower Manhattan district possible, which is a temptation I do not particularly want to see available.

[traininthedistance]

Regarding the matter of using regions to take cognizance of them, I was never clear how using regions worked mechanically to force/influence changes in maps (just as I am not clear exactly how to measure erosity except by eye, even though I keep asking that we work on  that issue, and try to agree on the best approach that makes stuff look appealing to the eye, and  on that one I need your mathematical mind to help me), as opposed to just being a useful tool to find micro-chops, whatever one might want to do with them. Perhaps you might explain that.

On the issue of compactness, maybe there is no good solution, but it is a negative for a CD to just wander all over the state, like that AZ CD that went from Sedona to Snow Low via the Indian reservations. Maybe erosity measures that we have not yet defined, is the best that we can do. Sometimes unfortunately the mind of man is just too inadequate to fashion rules that really work on a global basis. Such is life.

One of my observations from public discussions of gerrymandered maps is that what bothers people are the really gross shapes that have nothing to do with natural geography. They don't mind river bends and modest deviations from a straight line. They do take offense at shapes that create unnatural deviations from regular shapes. In a sense the public has a threshold where a district is shaped well enough, beyond which they'd rather concentrate on effects other than the shape such as geographic integrity or competitive districts. Most mathematical models of compactness continue to reward improving the shape ad infinitum with no natural threshold. One goal is build in a sense of a threshold based on the shape of the underlying geography.

Let's use pentonimoes as counties with uniform population in a perfectly rectangular state. Here's an example I found at random on google search.



Now suppose we have to divide this into 4 districts. Clearly there are a wealth of ways to group these 12 counties into contiguous groups of 3 pieces each. Since the ideal division without counties would be four rectangles that are 3 x 5, most compactness formulas are going to reward whatever mechanism gets you there. If the formula entertains chops then it would force so many chops to get those rectangles that I expect the public would be hugely unhappy. So we recognize that something has to be traded between the shape and the number of chops.

Traditional formulas that try to work with the compactness of an area would generally consider a district made of the magenta, blue, and light blue counties in the NW corner more compact than the pink, purple and orange district in the NE corner. That's because it's more square or circular in shape than the elongated district I describe for the NE. Yet, I contend most ordinary observers would say that the elongated one makes the better district. We would describe it as less erose, and from that I conclude that one has to look more at the perimeter than at the area. In particular the internal perimeter is what matters to the public observer, because they will always forgive erose shapes due to the external border of their state.

For this simple example one could start by finding the division that minimizes the total perimeter of all districts. The outer perimeter is the same for every plan so that can be subtracted from that total. The difference that is left counts for each district on the boundary so it should be divided by two to get the unique amount of perimeter created by the division into districts.

This works well when all the boundaries that are under consideration are built from straight lines. But suppose that the boundaries are sometimes straight and sometimes winding rivers. A pure formula like the one I just described is going to be strongly biased towards avoiding putting winding county edges on the perimeter of the district because it adds to the length without changing the area. Yet my experience is that the public sees no reason not to treat the county river boundary as equal to the straight line segment as long as there's a bridge across the river on that segment.

My solution for this is to count segments instead of the actual distance. Each boundary between two different counties on either side of the district boundary count as a segment. On the average for the straight line pentominoes it is equivalent to the actual length, but it has none of the problem of biasing against naturally wiggly county lines.

In an upcoming post I'll address the connection between this type of erosity and chops.

This is a really good post and I can't really think of anything to add to it at the moment. I have exactly the sorts of issues with traditional "geometric" compactness measures that you lay out here, and definitely prefer a regime that focuses on getting to "good enough" and then strives to keep metros, natural geographic regions, and the like together.  Counting segments (and, possibly, finding a way to rank segments so that some connections are discouraged from use) seems like a good step towards recognizing that some natural boundaries just are erose, and that doesn't make them necessarily worse.

[traininthedistance]

Been too busy to attend to fathoming Muon2's little rectangle with the colored boxes, but my first step  would be to number each box (using some utility on my computer), and repost it, for discussion purposes. Mike, if he wants to spend the time, of course could do that himself.   Then we can talk about numbered boxes, and I can better understand what he means by "segments." Thanks.

The idea re MSA's of just dealing with the core county may be a good one, except we already have the county chop concept, so if it is just the core county, what is the additional overlay that is in play here?

The idea is that some MSAs are large enough, and/or disrespect county lines enough, that there are often multiple "core counties", and that keeping those together should be a priority.  You can define the core by commuting patterns or urbanized areas; I think that the latter is clearly a better metric, though it may be trickier to work with in some ways.