Most Democratic Gerrymander possible

[Skill and Chance]

Using a 57-58% Obama 2008 minimum criterion for likely Democratic districts, ignoring Blue Dog opportunities, and fully maintaining all VRA Section 2 districts, here are some of the limits I've found:

WA: Commission
OR: 4D/1R
CA: Commission
AZ: Commission
NM: 2D/1Swing
CO: 5D/2R
NV: 3D/1R
UT: 3R/1D
NE: 2R/1D
KS: 3R/1D
OK: 4R/1Swing (OKC to Tulsa 51% Obama 2008 district, looks like NC-12)
TX: Don't know, probably something like 20R/16D?
MN: 6D/2R
IA: 2D/1R/1Swing
IL: 12D/6R
WI: 6D/2R
MI: don't know, thinking 10D/4R?
OH: I think 10D/6R
KY: 5R/1D (can't make 2 D-PVI seats)
MO: don't know
AR: 3R/1D
LA: 4R/2D
MS: 2R/2D
TN: 2D/6R/1Swing (54% Obama 2008)
AL: 5R/2D
GA: 7R/7D (seriously, with heavily Obama seats)
FL: don't know- remember FDF
SC: 5R/2D
NC: 7D/6R with liberal Obama districts, more if creating Blue Dog districts
VA: 7D/4R
MD: 7D/1R
PA: probably 11D/5R/2Swing?
NJ: commission
NY: 24D/3R realistically
CT: make all 5 equally as D as the state
RI: see CT
MA: see CT
NH: Option of 2 Swing or making Kuster's seat 60% Obama for 1D/1R
ME: 2D, see CT

So that would be at least a Dem gain of 30 seats in a 2012 environment over what they actually had.

 

[Skill and Chance]

This also shows that if 2009 was the redistricting year, Democrats would likely have held the House continuously since 2006, which further implicates gerrymandering.  It doesn't matter whether who you think would have won control in 2012 on a fair map.  The fact that a party can draw a 2006 or 2010 proof map should be scary enough.

[Skill and Chance]

I'm not sure your criteria works for IL. Obama's home state advantage caused a large overperformance in 2008, particularly in some suburban areas. One result was that the Dems tried to draw a 13-5 map, took 12, but are now down to 10-8. The three downstate CDs should be no more than 2, and Dold's results in IL-10 show that the PVI there due to Obama is misleading.

I went with what was actually enacted in IL and MD because they were D controlled.  In the case of AR, I have seen a 57% Obama district demonstrated here.  I agree in practice that 61-62% Obama is closer to the safe Dem district cutoff in IL and I believe that is what the legislature did with all the Chicago districts.  Clearly many of these districts on the hypothetical Dem gerrymanders would have been lost for a cycle in 2010 and 2014.