So, all estimates as of late in Pennsylvania losing a seat, and falling to 17 seats. In 2018, the old gerrymandered Pennsylvania map, passed by the Republican Legislature and Gov. Tom Corbett after the 2010 census, was struck down by the Pennsylvania Supreme Court. Subsequently, the still-Republican Legislature and Democratic Gov. Tom Wolf were unable to come to agreement on a new map, with Wolf vetoing the maps passed by the legislature. As a result, the Pennsylvania Supreme Court handed down the following map:
With Wolf holding the governorship until 2023 and the legislature looking almost certain to remain in Republican hands, odds are that we will see a similar impasse after the 2020 census, which would result in another court-drawn map. I don't expect the Court would largely change its criteria from 2018, meaning that the new map would probably somewhat resemble the current map. To see where the changes would be, we examine the population changes across the state.
(The following all uses 2010-2018 data)
From 2010 to 2018, the state as a whole grew 0.8%. Since Pennsylvania is falling from 18 to 17 seats, each congressional district thus grows in population by 1.008*18/17 = 1.0672 or 6.72%. The following map shows how much less (or more) than 6.72% each county has grown:
Formula: (County % change 2010-18) - 6.72%
This map clearly indicates that the largest part of the population falloff comes from the west and northwest parts of the state. In fact, the boundaries of the 15th Congressional district are almost visible as the deepest red section of the map.
Counties mostly/completely in CD 15 are shaded
The 15th district also is surrounded by other areas and districts which are losing a substantial share of their populations, which should make it even easier to carve up between its neighbors.
In addition to examining the county population change relative to the change in a congressional district, we can look at overall change in fraction of a congressional district (as in "how much less" of a congressional district a county counts for versus in 2010)
Doing this yields the following map:
Formula: (2018 County Pop.)/((2018 State Pop.)/17) - (2010 County Pop.)/((2010 State Pop.)/18)
From this, since the 2018 districts play very nicely on county lines, we can
roughly add up how much of a district each of the current districts loses:
Bucks County/Dist 01: Loses 5.2% of a district
Philadelphia/Dists 02-03: Loses 6.0% of a district (avg each district loses 3%)
Montgomery County/Dist 04: Loses 3.4% of a district
Delaware County/Dist 05: Loses 4.2% of a district
Chester County/Dist 06: Loses 1.4% of a district
Lehigh and Northampton Counties/Dist 07: Loses 2.4% of a district
8th District Area (including all of Luzerne, Monroe): Loses 8.6% of a district
9th District Area (including all of Berks): Loses 6.4% of a district
10th/11th Districts Area (York, Lancaster, Dauphin): Loses 4.8% of a district (avg each district loses 2.4%)
12th District Area (including all of Centre, Montour, Northumberland): Loses 8.1% of a district
13th District Area (including all of Cumberland): Loses 5.7% of a district
14th District Area: Loses 9.8% of a district
15th District Area (including all of Cambria): Loses 10.7% of a district
16th District Area (including all of Butler): Loses 9.3% of a districtAllegheny and Beaver Counties/Dists 17-18: Loses 13.9% of a district (avg each district loses 7%)
(Split counties have been added to the area for the district which contains the largest part of it; the only counties in which the split is somewhat close are Cumberland and Centre, neither of which really contribute to the sum; in fact Cumberland is the only county that manages to barely
gain in terms of districts, increasing by 0.017% of a seat.)
From this, again, the 15th is the district that loses the most and is the easiest choice to cut. The next largest losses come in the 14th and the 16th. I'm unsure about the prospect of carving the 14th, but I expect it'd be more difficult due to the fact that it's in a narrow corner with the two Allegheny based districts immediately to the north that would be unable to take too large of a fraction of a carved 14th.
Nixing the 16th, on the other hand, would force the 15th to move substantially to the west and take up, at the very least, most of the northern part of the former 16th, resulting in the 15th now being anchored in Erie and pretty much becoming more of a direct successor to the 16th, with the eastern part of the old 15th carved up by neighboring districts (most likely the 12th and 13th).
Either way, I think the 15th seat is the easiest to eliminate and carve up, which each of the other districts in the western and northern parts of the state) expanding substantially in area while most of the SEPA seats stay the same, only expanding slightly.
Am curious to know if the rest of you agree that the 15th is the likeliest to fall, or is there another viable alternative?
