Imagine a city with 50 voters. 60% vote for blue, 40% for red.
You need 5 districts with 10 people each. In a fair map, blue wins 3 districts. That is proportional.
But if red politicians draw district lines, they can pack many blue voters into 1–2 districts, where blue wins by huge margins and wastes votes.
Result: 60% of votes → 2 seats. 40% of votes → 3 seats.
That is gerrymandering: the mapmaker can shape the winner.
This is especially powerful in single-member district systems (like the U.S. House), where boundaries directly affect outcomes.
Packing means concentrating opposition voters in one district. They might win 80–90%, but only get one seat.
Cracking means splitting the rest across many districts, so they are just short of a majority everywhere.
Together, these tactics can turn a statewide minority into a legislative majority.
Source: packing and cracking
After each census, states redraw congressional districts every 10 years.
In 2010, Republicans won the Pennsylvania legislature and gained control over the 18-district map for the next decade.
They used that power aggressively.
Source: Redistricting in Pennsylvania
This is the map drawn by Republicans. Each district is colored by the winning party:
■ Democrats ■ Republicans
Notice the odd district shapes. They were not designed for coherent communities, but for political advantage.
District 7 became the symbol of this map. The Washington Post held a naming contest, and the winner was "Goofy kicking Donald Duck".
The district stretched about 80 km across five counties. At one narrow point, you could cross it in under a minute.
Why? To include selected Republican-leaning Philadelphia suburbs while bypassing Democratic pockets.
Outcome: Republican wins 59% to 40%.
Sources: Washington Post, PA-7 district
Look at the blue districts near Philadelphia — districts 1, 2, and 13.
Democrats won there by huge margins:
Those excess votes are "wasted" — only 50%+ is needed to win a seat. That is packing.
Source: PA elections 2016
Now look at suburban districts 6, 7, and 8. Democrats were present, but carefully split across districts.
Republicans won each seat with comfortable, not massive, margins:
This is cracking — spreading opposition voters so they cannot form a majority anywhere.
Source: PA elections 2016
Using actual statewide vote totals (sum across all 18 districts):
Democrats: 45.7% of votes → 5 of 18 seats (28%)
Republicans: 53.9% of votes → 13 of 18 seats (72%)
The gap between vote share and seat share is a classic gerrymandering signal.
Source: PA elections 2016
In January 2018, the Pennsylvania Supreme Court ruled that the 2011 map was unconstitutional.
Case: League of Women Voters v. Commonwealth of Pennsylvania.
The court held that the map violated Article I of the state constitution, which guarantees free and equal elections.
The legislature failed to agree on a replacement map by the court deadline, so the court imposed a new map.
Source: League of Women Voters v. Commonwealth of Pennsylvania
This is the court-drawn map. Compare it to the old one.
Districts became more compact and geographically coherent. No more "Goofy" shape.
■ Democrats ■ Republicans
Source: PA Supreme Court remedy (2018)
After the ruling, most of the old "Goofy" district area was reassigned into new districts 5 and 6 (with some parts in 4).
2018 results there: District 5 — 65%, District 6 — 59% for Democrats.
When boundaries are more compact and logical, the map better reflects the region's real political geography.
Sources: history of old PA-7, PA elections 2018
2018 statewide outcome:
Democrats: 54.9% of votes → 9 of 18 seats (50%)
Republicans: 44.7% of votes → 9 of 18 seats (50%)
Representation became much fairer than in 2016: seat share moved closer to vote share.
Source: PA elections 2018
A map is not neutral. In 2016, it turned 45.7% Democratic votes into 28% of seats. After judicial redistricting, the distortion dropped sharply.
Gerrymandering means voters do not choose politicians — politicians choose their voters.
Sources: LWV v. Commonwealth of Pennsylvania (2018), US Census Bureau, PA elections 2016