Here is another map of what Democrats could do with congressional redistricting, this time in New Jersey. New Jersey redistricts with a bipartisan commission that has a tiebreaker, so no matter how many legislative seats they win, Democrats can't control redistricting. If they could, however, they could theoretically draw a map for 10 Democrats and 2 Republicans, a drastic improvement over the state's current 7 D-6 R delegation. These would not all be ultra-safe seats, they would require legitimate Democrat candidates running real campaigns, but they are Democratic-leaning enough that given those circumstances the Democrats should be able to win no problem.
New Jersey is losing a seat, going from 13 seats to 12 seats. Frank LoBiondo's seat becomes bluer. Jon Runyan and Leonard Lance are drawn into completely different, much bluer versions of their current districts. Scott Garrett and Rodney Frelinghuysen will almost certainly fight to the death in a primary. Chris Smith keeps a lot of his territory but his home is drawn out of his district and Runyan might primary him rather than seek re-election in his new, radically redrawn district.
Although this is a gerrymander, it is actually fairly clean, at least by my standards. I made a point of minimizing splitting municipalities (townships, boroughs, and cities). I split in a few cases to beef up minority voting power and in some other cases to achieve population equality, but barely any municipalities are split for partisan purposes.
As a final note, I should point out that some (mostly Democratic) areas are missing votes on Dave's app. So a few of these districts might be a point or two bluer than the numbers suggest. Anyway, let's get on with the show.
Here's the whole state.
NJ-01
Incumbent: Rob Andrews (D-Haddon Heights)
Old Vote: Obama 65 McCain 34
New Vote: Obama 62 McCain 38
Average: Dem 59 Rep 41
Description: Andrews sees his district weakened a bit to hurt LoBiondo and Runyan, but he keeps the bluest district in the state aside from the two minority-majority ones. He shouldn't have much to complain about.
NJ-02
Incumbent: Frank LoBiondo (R-Ventnor)
Old Vote: Obama 54 McCain 45
New Vote: Obama 56 McCain 44
Average: Dem 55 Rep 45
Description: LoBiondo sees some of his Republican areas carved out and put into NJ-01, and he adds blue areas in Gloucester County. LoBiondo is currently ok in his D+1 district, but this district is slightly bluer and has some unfamiliar territory. Also, the Democratic city of Salem is missing some votes in Dave's App so it might actually be O57 M43 but I'm not sure. Plus, LoBiondo has faced nobodies pretty much his entire career, but what happens if the bluer hue of this district attracts the likes of St. Sens Jeff Van Drew (D-Dennis Township) or Jim Whelan (D-Atlantic City)? My mom grew up in this district and I've been here many times, so it would be personally satisfying for me to see LoBiondo go down.
NJ-03
Incumbent: Jon Runyan (R-Mount Laurel Township), Chris Smith (R-Hamilton Township)
Old Vote: Obama 52 McCain 47
New Vote: Obama 56 McCain 44
Average: Dem 52 Rep 48
Description: This is basically Jon Runyan's district, although both he and Smith have been drawn into it. This district shifts north and in the process becomes more Democratic. Runyan is somewhat of an accidental congressman, a shitty candidate who got swept in by the wave over former Rep. John Adler (D-Cherry Hill) (RIP). There's no way he can win this district, so he will probably migrate over to the 4th to face a primary against Chris Smith...and get his ass kicked.
NJ-04
Incumbent: OPEN
Old Vote: Obama 47 McCain 52
New Vote: Obama 41 McCain 59
Average: Dem 42 Rep 58
Description: This GOP vote sink helpfully scoops out the parts of GOP-trending Monmouth County that gave Rush Holt a scare in 2010. Chris Smith is favored to defeat Jon Runyan in a primary here.
NJ-05
Incumbent: Scott Garrett (R-Wantage Township)
Old Vote: Obama 45 McCain 54 (NJ-05), Obama 45 McCain 54 (NJ-11)
New Vote: Obama 41 McCain 59
Average: Dem 39 Rep 61
Description: The two reddest districts in New Jersey, the 5th and the 11th, have been combined into this new 5th. Rodney Frelinghuysen's home has been drawn into the black-majority 9th (the old 10th's successor), which is obviously unwinnable for him, so he would run here. Garrett is probably favored here, but Dems should cheer for Frelinghuysen as he is moderate about 10% of the time (compared to 0% for Garrett) and a Democrat can't win in this Republican vote sink.
NJ-06
Incumbent: Frank Pallone (D-Long Branch)
Old Vote: Obama 60 McCain 39
New Vote: Obama 59 McCain 41
Average: Obama 57 McCain 43
Description: Pallone faced a tough challenge in 2010 from Highlands mayor/teabagger Anna Little but ended up fending her off by double digits. This district gets much less gerrymandered and basically stays the same partisan-wise. So Pallone should be fine here.
NJ-07
Incumbent: Bill Pascrell (D-Paterson)
Old Vote (NJ-08): Obama 63 McCain 36
New Vote: Obama 58 McCain 42
Average: Dem 57 Rep 43
Description: Bill Pascrell won't like this district because it gets less blue, but that's called taking one for the team. He just has to get out there and campaign and not be lazy. That's all it will take to call this Safe D.
NJ-08
Incumbent: Steve Rothman (D-Fair Lawn)
Old Vote (NJ-09): Obama 61 McCain 38
New Vote: Obama 60 McCain 40
Average: Dem 61 Rep 39
Description: This district shifts north, becoming less Hudson County-based and more Bergen County-based. It's still safe for Steve Rothman, who lives in Bergen anyway.
NJ-09
Incumbent: Donald Payne (D-Newark), Rodney Frelinghuysen (R-Harding Township)
Old Vote (NJ-10): Obama 87 McCain 13
New Vote: Obama 78 McCain 22
Average: Dem 74 Rep 26
Description: This district is a bit bluer than the numbers suggest due to missing votes in Newark, but honestly, who cares? It's obviously super-safe D either way. It remains majority-black (50.4%) among the total population but only plurality black (49.4%, vs. 28.7% white) among the 18+ crowd. However, I don't think this will be a VRA problem. For one thing, black voters clearly still dominate this district, plus New Jersey isn't covered by Section 5 of the VRA so I don't think retrogression is an issue here.
NJ-10
Incumbent: OPEN
Old Vote (NJ-07): Obama 51 McCain 48
New Vote: Obama 57 McCain 43
Average: Dem 54 Rep 46
Description: I'm counting this as the successor to Leonard Lance's old district, even though Lance doesn't live here. Leonard Lance successfully portrayed himself as a moderate in 2008, getting the endorsement of the New York Times en route to beating Linda Stender. But this district is much bluer, and since getting to Congress, Lance has cast a number of votes that threaten to reveal his true right-wing colors. It's questionable whether he could win a district so much bluer than his current one.
NJ-11
Incumbent: Leonard Lance (R-Clinton Township), Rush Holt (D-Hopewell Township)
Old Vote (NJ-12): Obama 58 McCain 41
New Vote: Obama 60 McCain 40
Average: Dem 54 Rep 46
Description: Rush Holt, a solid progressive, faced a scary match against self-funder Scott Sipprelle in 2010, but eventually hung on by high single digits. The problematic Monmouth County portion of his district has been chopped off, and his district has gotten slightly bluer. If anything, it might be a point bluer than the numbers suggest, because Dave's App is missing some votes in heavily Democratic Trenton, the state capital. Leonard Lance could also run here but probably doesn't want to run in such a deep-blue district with lots of unfamiliar territory.
NJ-12
Incumbent: Albio Sires (D-West New York)
Old Vote (NJ-13): Obama 75 McCain 24
New Vote: Obama 72 McCain 28
Average: Dem 73 Rep 27
Description: As with the new 9th, it's missing Dem votes (in Jersey City), but it doesn't matter because it's such a ridiculously blue district anyway. Also as with the new 9th, it is a minority-majority district which has been slightly diluted. It's 51% Hispanic total, 48% VAP (vs. 32% white VAP). See the description of the 9th for why I don't think there are any VRA issues here--plus, if I recall correctly, the current 13th is not even majority Hispanic among total population to begin with.