BREAKING: PA Supreme Court issues new map

[BumRushDaShow]

13. Sam Wang and Princeton Consortium response to the map

Introducing the new Pennsylvania Congressional map
February 19th, 2018, 3:20pm by Sam Wang



Here’s the new Congressional map for Pennsylvania, drawn by the special master. It splits 13 counties, less than any plan offered to the court. The only plan that splits fewer counties is the “compact D gerrymander” that the Princeton Gerrymandering Project posted over the weekend. Our plan scores comparably to or better than the special master’s plan on the metrics the court set out (fewer county and municipality splits, performs just as well on compactness metrics).

As we showed over the weekend, it is just possible within the Pennsylvania Supreme Court’s rules to allow a plan that reaches partisan balance, i.e. a 9 D, 9 R outcome for a 50-50 statewide vote. However, those rules bias the range of possibilities in favor of Republicans, so that a Republican gerrymander – one of the proposals on the table – was also a possibility.

It appears as if the special master was trying to achieve partisan balance (as opposed to, say, picking a plan that was in the middle of the range of possible maps). His map – and the one we gave over the weekend – show that even under the constraint of compactness and not splitting political jurisdictions, it is still possible to undo the effects of population clustering. Notably, he did so while keeping most population centers together.

It now seems clear that the Pennsylvania GOP made a serious tactical error. The governor and Democratic legislators had offered a plan that would have retained some GOP advantage. The new plan erases that advantage entirely. In our analysis, based on the 2016 vote the new map produces 5 Democratic districts, 7 Republican districts, and 6 tossup districts. The maximum likely performance by Democrats in 2018 would be 11 seats, a gain of 6 seats over their current representation. That gain would be one-fourth of the 24 seats they need to win control of the House of Representatives. Of course, some of those gains could also go away in a later year that was good for Republicans. That’s the point of electoral competition.

http://election.princeton.edu/2018/02/19/introducing-the-new-pennsylvania-congressional-map/