On Monday, the Pennsylvania Supreme Court adopted a new congressional map for 2018 that's close to a best-case scenario for Democrats. The map, drawn by a court-appointed special master, doesn't just undo the gerrymander that's produced a 13-5 seat GOP edge since 2012. It goes further, actively compensating for Democrats' natural geographic disadvantage in the state. Under the new lines, Democrats have an excellent chance to win at least half the state's 18 seats.

In redistricting, fairness is always in the eye of the beholder. Democrats see the new plan as fair because it proactively helps them win an even share of seats. Republican see the new plan as a Democratic gerrymander issued by a partisan court majority. But no matter how you look at it, the ruling is a big boost to Democrats' chances of winning a House majority. If Democrats pick up four seats — essentially breaking even in Pennsylvania — that's a sixth of the 24 seats they need.

Apoplectic Republican state legislators are evaluating their options for appeal. But the U.S. Supreme Court has already declined once to intervene in the Pennsylvania case, so it's likely the new map will be in place this November (although the March 13 special election in PA-18 will take place under the old lines). The filing deadline for the May 15 primary is March 20, so incumbents and candidates in drastically altered districts have about a month to plot their next moves.

Any discussion of the partisan impact of the new map must begin with the caveat that Democrats already had great opportunities to win five GOP-held seats in 2018 under the old lines. Under the new lines, all five Democratic incumbents still have safe seats to run in, and Democrats still have great opportunities in five GOP-held seats. But new districts have dramatically increased the quality of those five pickup opportunities.

Under the new lines, retiring GOP Rep. Pat Meehan's open seat becomes a safe Democratic district anchored by Delaware County, and retiring GOP Rep. Charlie Dent's open seat in the Lehigh Valley gets about five points more Democratic. In the Philadelphia suburbs, GOP Reps. Ryan Costello and Brian Fitzpatrick get less favorable lines. And in the Pittsburgh suburbs, GOP Rep. Keith Rothfus's seat moves from safe to very vulnerable.

The new map also gives Democrats two new long-shot targets in case 2018 is a wave: it reconfigures GOP Rep. Scott Perry's York district to include Harrisburg, making it much more competitive. And it also reunites Erie in GOP Rep. Mike Kelly's district, making it a slightly more enticing target for Democrats. The only GOP winner in the new map may be Lancaster GOP Rep. Lloyd Smucker, whose GOP-leaning seat becomes safe Republican territory.

Interestingly, both PA-18 special election nominees, Democrat Conor Lamb and Republican Rick Saccone, are drawn out of the reconfigured 18th CD in the new plan. If Saccone wins on March 13, he'd likely need to file in the much more Republican 14th CD (which includes most of the current 18th CD) to keep his seat. But if Lamb wins, he'd likely need to run in the new, highly competitive 17th CD, where GOP Rep. Keith Rothfus lives, to stay in Congress.

Both Lamb and Saccone would only have a week between the March 13 special election and the March 20 filing deadline to decide where to run in November. There's no requirement that candidates live in the district they seek to represent, but all candidates are required to file 1,000 signatures for November ballot access.

Several incumbents are also caught in this game of musical chairs. For example, Democratic Rep. Brendan Boyle's district was split in half, and he could run in either the open 2nd (in Philadelphia, where he lives) or the open 4th in suburban Montgomery County (where most of his current constituents live). If he were to run in the 2nd, it could open up the new 4th CD for former Democratic Rep. Allyson Schwartz to reclaim her old congressional seat.

Adding to the confusion, the Pennsylvania Supreme Court essentially threw out all the old district numbers and renumbered all but one of 18 seats. To help make sense of it all, here are the old and new maps as well as old and new Cook PVI scores and race ratings for the redrawn seats. Subscribers can click here to read the new bottom lines in these districts.

Old Map

Image and video hosting by TinyPic

New Map

Image and video hosting by TinyPic

Pennsylvania District Changes


More from the Cook Political Report