Big Redistricting News Out Of PA!

[Torie]

In the new political dynamic of PA, a non gerrymandered map might not gain much for the Dems at the Congressional level. Indeed, Cartwright, who represents what was thought to be a Dem vote sink in the Scranton-Wilks-Barre area but where Trump made massive gains (offset some by Schuylkill County being in the CD), might be put at risk. But that would be offset by PA-07 going to the Dems, which was kept Pub by an insane precinct by precinct gerrymander. PA-08 would get a tad more Dem, but it would still be a swing district. I am not sure what the basis of the lawsuit is, unless it is anticipating a SCOTUS decision. I suppose it could be based on similar broad brush language in the PA Constitution about equal protection or whatever, but it would be rather novel to rely on that.

[Torie]

Back in 2013 I looked at PA using DRA as the muon rules were first being fleshed out. With help from Torie, traininthedistance, and jimrtex, I came up with a balanced neutral plan. I couldn't find my drf file from back then, so I reconstructed it with a couple of tweaks to reflect the current version of the rules.



Chester is the only macrochopped county smaller than a CD, and only three other small counties have regular chops. No city/borough/township is chopped except Philly, and no ward within Philly is chopped. Obama won 11 of the 18 CDs in 2008. DRA population deviations and current PVIs for the CDs are:

CD 1: (-42) D+22
CD 2: (-497) D+39; BVAP 52.6%
CD 3: (+180) R+5
CD 4: (-1808) R+5
CD 5: (+1704) R+16
CD 6: (-691) R+0
CD 7: (-616) D+8
CD 8: (+1566) R+2
CD 9: (+1078) R+15
CD 10: (-1173) R+20
CD 11: (-491) R+2
CD 12: (+1919) R+8
CD 13: (-636) D+17
CD 14: (+921) D+12
CD 15: (-2359) R+7
CD 16: (+963) R+13
CD 17: (-1047) D+0
CD 18: (+1006) D+2

This might give some sense as to what a new neutral map might produce.

I just drew my map, which attempted to follow the Muon2 rules, and see that it unsurprisingly is quite similar to his (which I am now just seeing), except for how Chester is dealt with. PA-03 remains solidly Pub, no matter how the lines are drawn. PA-15 and PA-17 do move to the Dems by about by a bit more than one point in PVI, but PA-15 remains a swing CD, and Dent if he had run for reelection, would certainly have easily held it. Trump carried PA-17 by 7.5 points, rather than 10 points. I did not crunch the numbers for PA-06, but I suspect it moves a bit to the Pubs over the current CD. (In Muon2's map, it moves a lot to the Pubs.) PA-08 moves very slightly to the Dems, but remains a swing district. As I said, the only Pub CD which disappears is PA-07. So maybe the Dems net about two seats, but it could easily be just one. The Pub gerrymander just did not harvest that much for them, at least as things have evolved since it was originally drawn.

Oh, this business that Brady needed more white votes, and thus needed a CD that left Philly, is just not supported by the numbers. In my map, his CD is 23.5% BVAP. I suspect some Pubs made that one up as their own little urban legend, to justify their gerrymander as not entirely partisan in that it helped Brady, and Krazen picked up on it to troll us.

[Torie]

Back in 2013 I looked at PA using DRA as the muon rules were first being fleshed out. With help from Torie, traininthedistance, and jimrtex, I came up with a balanced neutral plan. I couldn't find my drf file from back then, so I reconstructed it with a couple of tweaks to reflect the current version of the rules.



Chester is the only macrochopped county smaller than a CD, and only three other small counties have regular chops. No city/borough/township is chopped except Philly, and no ward within Philly is chopped. Obama won 11 of the 18 CDs in 2008. DRA population deviations and current PVIs for the CDs are:

CD 1: (-42) D+24
CD 2: (-497) D+39; BVAP 52.6%
CD 3: (+180) R+8
CD 4: (-1808) R+17
CD 5: (+1704) R+15
CD 6: (-691) R+3
CD 7: (-616) D+8
CD 8: (+1566) R+1
CD 9: (+1078) R+20
CD 10: (-1173) R+17
CD 11: (-491) D+0
CD 12: (+1919) R+13
CD 13: (-636) D+17
CD 14: (+921) D+10
CD 15: (-2359) R+0
CD 16: (+963) R+9
CD 17: (-1047) R+9
CD 18: (+1006) R+3

This might give some sense as to what a new neutral map might produce.

Edit: fixed the PVIs by using old voting districts

Muon2’s map is drawn to minimize county chops, but must have been crafted before his rules included pack (fewer CD’s located wholly within the boundaries of a metro area than the maximum possible) and cover (more CD’s wholly or partially located within the boundaries of a metro area than the minimum possible) penalties with respect to multi-county metro areas (as defined by the US census, except that more rural counties included therein are excised per an algorithm fashioned by the most indefatigable and creative Jimrtex).    

His map as compared to my cover and pack penalty free effort below (the multi county metro areas as defined by Jimrtex are outlined out on my map) has cover and pack penalties for the Philly and Allentown metro areas (with the ones for Allentown easily avoided by chopping into Carbon rather than Lehigh County), and a cover penalty for the Pittsburg metro area.  By tri-chopping Alleghany County, he also generates an extra macro chop, which may or may not generate more erosity penalty points in that county than my map does).  Given his monomaniacal focus on minimizing county chops, he does however have one fewer county chop than the map below. ☺

The BVAP for PA-02 is 48.4% by the way in the map below.  It also contains no municipality chops (or ward chops in Philly), other than the one that is unavoidable (i.e. Philadelphia, which really does not count since its lines are co-terminous with the county lines).

[Torie]

Thank you. My guess at PVI relying in part on the Toomey numbers which I think are more indicative of party strength going forward than the Trump coalition, is that PA-01, 02, 07, 13 and 14 are Dem bastions, PA-17 has a Dem PVI of about 2, PA-08 is a swing seat with a Pub PVI of maybe 1 and quite stable overall, PA-06 and PA-15 both have a Pub PVI of about 2 (with PA-06 trending Dem, and PA-15 fairly stable overall), and  the other 9 seats are Pub bastions. After the 2020 census, one of the Pub bastion seats (i.e. PA-05) will disappear.

[Torie]

Here's the definitions worked out on the subject of chops (edited to reflect current use). Chops involving more than one fragment of a district are still just a chop. However, chops involving multiple fragments will typically have higher erosity, as each fragment counts separately for connections. The creates a small disincentive for fragmented chops, but that fragmentation might preserve towns or wards from additional chops.

Definition: Chop. A single chop is the division of a geographic unit between two districts. A second chop divides the unit between three districts. In general the number of chops is equal to the number of districts in that unit less one.

Definition: Chop size. In units with a single chop, the size of a chop is the population of the smaller district within the unit. For districts with more than one chop, chop sizes are measured in order from the smallest populated district in the unit up to but not including the district with the largest population in the unit.

Definition: Macrochop. A macrochop is one or more chops in a county that has a total size in excess of 5.0% of the quota. When a macrochop of a county occurs, the subunits of the county must be considered as if they were units as well. Note that macrochops may only apply to counties with a population of more than 10% of the quota, and must apply to counties with more than 105% of the quota.

Item 10: CHOP measures the integrity of geographic units in a plan. The CHOP score is the total of all county chops. In counties with a macrochop, chops of county subunits are added to the CHOP score, however VTDs that span county subdivisions do not increase the CHOP score.

Ugh, my first response died in a browser crash. I just have to say, for someone that places county integrity so high, I don't understand why you don't place the criteria I mentioned higher. If a county can support a certain number of districts within its boundaries, I think it should be required to do so. Philadelphia County should have two districts completely within its boundaries.

Thank you. My guess at PVI relying in part on the Toomey numbers which I think are more indicative of party strength going forward than the Trump coalition, is that PA-01, 02, 07, 13 and 14 are Dem bastions, PA-17 has a Dem PVI of about 2, PA-08 is a swing seat with a Pub PVI of maybe 1 and quite stable overall, PA-06 and PA-15 both have a Pub PVI of about 2 (with PA-06 trending Dem, and PA-15 fairly stable overall), and  the other 9 seats are Pub bastions. After the 2020 census, one of the Pub bastion seats (i.e. PA-05) will disappear.

I think SWPA could be drawn better. Attaching Butler County to the remainder of Allegheny seems like a Republican strategy. I think a more fair map would attach the remainder of Allegheny with Beaver County.

Doing as you suggest would generate another county chop. That is the beauty of this system. Partisan figures are irrelevant. At the end of the process, one then has a series of high scoring maps (one usually will end up with more than one competitive map, because with more chops, one can in most cases reduce erosity), and one can certainly then have a system that rewards maps with a lower partisan "skew" as Muon2 puts it. So my Butler addition was not a partisan plot, but just how the cookie crumbled given the 2010 census numbers. After 2020, it may will be that northern Allegheny and Butler would get a divorce as it were. What you suggest would still leave you with a Pub CD in any event, unless things change a lot politically.