To understand how Republicans pulled this off, we need to take a close look at the map. To that end, I've superimposed the state's congressional district boundaries over a map produced by Ryne Rohla of Washington State University, showing precinct-level 2016 presidential election results. This lets us see how the district boundaries relate to where Democratic and Republican voters actually live.
It's hard to tell exactly what's going on in this bird's-eye view, in part because a lot of the Republicans' magic happens in the snarled thicket of district boundaries in the southeast corner of the state around Philadelphia. So let's start by zooming in on District 7, held by Republican Patrick Meehan.
District 7 is one of the nation's most famous gerrymanders in part because it bears a striking resemblance to Goofy (on the right) kicking Donald Duck (on the left).
To wrest a Republican seat out of this region, Republican lawmakers paired a significant chunk of the north and west Philadelphia suburbs (Goofy) with a wide swath of the countryside outside Lancaster and Reading (Donald). Lawmakers had to get extremely creative to pull that off, narrowing the width of the district to just about 1,000 feet at the point where Goofy's foot makes contact with Donald's behind.
They had to be careful — pull in too many Democratic precincts and Meehan's seat would be in jeopardy. Conversely, incorporating the wrong Republican precincts would jeopardize GOP majorities in neighboring districts. In the end, Meehan won with a comfortable 19 percent vote margin in 2016.
Let's look now at two of those neighboring districts — PA-6, held by Republican Ryan Costello, and Republican Lloyd Smucker's seat in PA-16.
You can see the ghost of Donald Duck in the negative space between the two districts. There's also something interesting happening in the city of Reading. There, PA-16 sends out a protuberance to capture Reading's Democratic-leaning voters and bring them safely into the fold of Smucker's district, where they're offset by all the Republican voters surrounding the city of Lancaster.
This has the effect of narrowing Smucker's margin of victory — just 11 percent in 2016 — while creating a safe seat in PA-6 for Costello, which would otherwise be jeopardized by all the Democratic voters the district siphons off the Philadelphia area.
Again, Republicans' attention to detail is exquisite. PA-16's jaunt to Reading at one point narrows to just 500 feet wide, surrounded by PA-6 to the northwest and PA-7 to the southeast. A five-minute stroll from Reading's Pleasant View cemetery, down Lutz Drive to the Cacoosing creek would traverse three separate congressional districts — all held by Republicans.
Other parts of the state prove that you don't always need a scalpel to perform feats of redistricting — sometimes a sledgehammer will do. The Harrisburg metro area is a case in point. The city is a Democratic stronghold, a potential problem if you're trying to create safe Republican seats.
Republicans' solution? Just draw a line through the middle of it.
Harrisburg's Democrats are divided, with some going to Lou Barletta's 11th District and the rest staying in Scott Perry's 4th. One Democratic stronghold gets diluted across two safe Republican districts, with a few Democratic stragglers in Hershey shunted off to Republican Charlie Dent's District 15 for good measure.
One additional sign of just how aggressively gerrymandered the state's districts are: In the 2016 elections, three incumbent Pennsylvania representatives — Republicans Mike Kelly and Tim Murphy, and Democrat Brendan Boyle — ran completely unopposed. There's not much to be gained from running opposing candidates in districts where the outcomes are all but determined by how the borders are drawn.
But according to the Pennsylvania Supreme Court, those days are over. The state's Republican lawmakers have until Feb. 15 to submit a nonpartisan district plan with Democratic governor Tom Wolf's approval. If they fail to do so, the court will draw the districts itself.