Based on 2012 results only, which state gerrymander flipped the most seats?

[Nyvin]

Arizona is only a "gerrymander" as it was drawn intentionally to produce competitive seats.   All three of the competitive seats still have a Republican lean, so it's extremely hard to call it a big win for the Democrats.   The Dems just had a good set of candidates to run there.

I would say either Ohio or Pennsylvania would be the biggest gain for map drawing,  although in the case of PA the Dems are really geographically concentrated, so probably Ohio.  

In Michigan you can draw three more Dem seats,  two more in the Detroit area and a third based out of Lansing and Jackson.   Which shouldn't be surprising considering even in 2014 the Dems won a majority of the House vote.

[Nyvin]

Arizona is only a "gerrymander" as it was drawn intentionally to produce competitive seats.   All three of the competitive seats still have a Republican lean, so it's extremely hard to call it a big win for the Democrats.   The Dems just had a good set of candidates to run there.

I would say either Ohio or Pennsylvania would be the biggest gain for map drawing,  although in the case of PA the Dems are really geographically concentrated, so probably Ohio.  

In Michigan you can draw three more Dem seats,  two more in the Detroit area and a third based out of Lansing and Jackson.   Which shouldn't be surprising considering even in 2014 the Dems won a majority of the House vote.

I won't argue with you about Michigan (I just disagree, per the VRA in particular, what a Muon2 metric map would do), but as to AZ, I would note that the law in AZ was that competitive seats were a sub factor subordinate to everything else, acting as a tie breaker. Mathis put it to the top of the list, in violation of the law, and then I think made them in two cases on the Dem side of the ledger to boot, but I won't argue that one with you either.

Addendum. I revisited Michigan, and drew a new map, following Muon2 metrics. What we find is that two seats flip to the Dems, MI-07 and 08, and based on the 2008 partisan numbers, three CD's move to tossups vis a vis the Pub gerrymandered map, MI-11, MI-02 and the red CD (MI-04 - I can't move the CD numbers for the moment, so the "4" number is in the wrong place). So on paper, that is a flip of 3.5 seats, and thus the national "winner," but in reality, all three tossup CD's would have been held by the Pubs (assuming Rodgers moved to MI-11 to run for re-election). That is particularly the case since all three toss up CD's trended pretty heavily Pub in 2012. In addition, not that it counts for anything for purposes of this exercise, but MI-09 gets rather marginal for the Dems, with a Dem PVI of 2.7%, which probably dropped down to maybe 2% in 2012.

So AZ to me is still the winner, since it did in fact flip three seats.

It's quite gratifying to see how many seats become tossup seats in Illinois, Ohio and Michigan, with good government, Muon2 metric, maps. That is yet another reason to push for their implementation across the Fruited Plain. May the Mainstream Partnership, and the Dem equivalent, multiply and thrive.

I guess this is more what I would think of





The majority of the "chops" outside of the Northern Detroit area are just tiny smidges to equal out population,  most of them don't affect PVI at all.  

The concept overall is pretty simple:   A Lansing based seat, a Kalamazzo-Battle Creek seat,  Grand Rapids seat, Flint-Saginaw seat, Ann Arbor seat,  about 5 Detroit seats, a "Thumb" seat, and 2 in Northern Michigan.   Then MI-6 is whatever is left, lol.

Here's the PVI for those maps:

1:  49.6% Obama
2:  53.7% Obama (was kinda surprised by this, wasn't intentional)
3:  49.4% Obama
4:  57.5% Obama
5:  62.3% Obama
6:  43.9% Obama
7:  53.7% Obama
8:  57.9% Obama
9:  55.7% Obama
10:  46% Obama
11:  56.7% Obama
12:  62.3% Obama
13:  74.3% Obama  (50.6% BVAP)
14:  75.6%  Obama  (51% BVAP)

If I'm counting right that's 8 seats that lean Dem, and another 2 that are probably swing seats (MI-7 and MI-2).   That would be AT LEAST three seats picked up from the current map, and possibly two more.

This map doesn't even make any weird turns or county chops either.    If you really want to go crazy you could make MI-2 lean Dem by adding the inner city part of Grand Rapids to it.   (In other words, make it the current MI-2, just add different parts of Kent County and take out parts of Ottawa).

Looking at the current MI map, it's pretty clear the GOP knew exactly what they were doing by splitting the Lansing area between districts 4, 7, and 8, putting Battle Creek with the Grand Rapids suburbs, and Ann Arbor in with MI-12...

[Nyvin]

You say PVI, but you really mean the Dem share of the vote. For PVI purposes the Dem share is the percentage found by dividing the Dem vote by the total Dem+Pub (eliminating all other votes). I'm not sure if your numbers are adjusted to the two-party share.

Since Obama got 53.7% of the two-party vote in 2008, an approximate PVI is found by comparing each of those percentages to 53.7%. Perhaps you did that in your analysis, but not in the table.

Here's the PVI for those maps:

1:  49.6% Obama
2:  53.7% Obama (was kinda surprised by this, wasn't intentional)
3:  49.4% Obama
4:  57.5% Obama
5:  62.3% Obama
6:  43.9% Obama
7:  53.7% Obama
8:  57.9% Obama
9:  55.7% Obama
10:  46% Obama
11:  56.7% Obama
12:  62.3% Obama
13:  74.3% Obama  (50.6% BVAP)
14:  75.6%  Obama  (51% BVAP)

If I'm counting right that's 8 seats that lean Dem, and another 2 that are probably swing seats (MI-7 and MI-2).   That would be AT LEAST three seats picked up from the current map, and possibly two more.

Yeah...I thought that would be obvious,   you subtract 52.9% from each Obama number to get the actual PVI.   Putting the percentage is just a little less work for me, lol.

[Nyvin]

Oregon has crazy state laws regarding redistricting.     I'm pretty sure all the counties east of the Cascades are considered a "community of interest" and can't be divided by state law ORS 188.010.  

Also Portland has 2 different communities of interest and has to be split east and west....I think going along the river.

And it's in the state law that the districts have to be connected with transportation links.

[Nyvin]

This was one of my offerings from 2013. It has 6 county chops, one of which is a microchop since we ere giving credit for those back then. I count a cover penalty of 1 in Balto and a pack penalty of 1 in Wash for a chop score of 8. It has 2 BVAP majority CDs (5 and 7) and one at 41% (CD 4). The partisan breakdown is 5D, 1e (CD-3), 2R for a skew of 0.

This would be a good map for Maryland honestly,  just give the GOP their darn northwest seat and be done with it.   One less thing for them to deflect on with the red state gerrymanders. 

If places like Texas and North Carolina had fair maps I'd be in favor of this.