From Elbridge Gerry's salamander district in 1812 to GPS-precise algorithmic map manipulation in 2022 — a complete breakdown of the techniques, tools, and tactics that let politicians choose their voters.
On February 11, 1812, Massachusetts Governor Elbridge Gerry signed a redistricting bill that created a state senate district of such extraordinary contortion that the Boston Gazette compared it to a salamander. A cartoonist added a head and wings. An editor combined the Governor's name with the creature's: "Gerry-mander." The name entered the language permanently — and so did the practice.
What Gerry's allies did with quill and parchment, modern mapmakers accomplish with precision software and terabytes of voter data. The goal is identical: draw lines that convert votes into legislative seats with maximum efficiency for one party, minimum efficiency for the other. The technology has changed. The cynicism has not.
Every gerrymander, no matter how complex, relies on two fundamental operations: packing and cracking. Mapmakers use them in combination to produce maps that convert a narrow vote-share advantage into a lopsided seat advantage.
Packing concentrates as many opposition voters as possible into as few districts as possible. If your opponent's voters are packed into one district, they win that one seat by a massive margin — say 90% to 10% — while all those "extra" votes accomplish nothing. Those votes are wasted on a victory that was already assured. In return, the remaining districts have fewer opposition voters, making them safer for your side.
Cracking splits a concentrated community across multiple districts so it never forms a majority anywhere. A city that might deliver a solid 55% for the opposition is divided into four slices, each absorbed into a larger surrounding district where its votes are diluted to 30% and easily overridden. The community has representation in four districts — and meaningful influence in none of them.
Step through the animation below to see how the same 25 voters can be carved into districts that hand one party a landslide — even when votes are nearly equal.
Every ten years, following the U.S. Census, every state must redraw its congressional and legislative district maps. In most states, that process is controlled entirely by the state legislature — the very politicians who stand to benefit from the outcome.
The U.S. Census Bureau releases population data at the block level — the smallest geographic unit. This data tells mapmakers exactly how many people live in each area and, combined with other sources, approximates where voters of different backgrounds live.
State parties and consultants layer in voter registration data, past election results, consumer data, and even social media information. Modern redistricting software can model how any proposed district boundary will behave in elections — before a single vote is cast.
Specialized software like Maptitude for Redistricting and custom-built tools allow mapmakers to run thousands of district configurations in minutes, optimizing for partisan advantage while technically satisfying legal requirements: equal population, contiguity, and in some states, compactness.
In most states, the legislature passes the new maps through a simple majority vote — the same party that benefits from the gerrymander controls the committee hearings, floor debates, and final vote. Public comment periods are often perfunctory. Alternative maps submitted by advocacy groups are routinely ignored.
Once signed by the governor, the maps govern every congressional and state legislative election for the next ten years. Legal challenges can delay implementation but rarely succeed in producing genuinely fair maps. The next opportunity to draw new maps: ten years away.
Gerrymandering is not an abstract problem of democratic theory. It has measurable, documented consequences for how Congress behaves, what policies get passed, and who gets represented.
Only about 14% of House seats are now considered genuinely competitive — down from roughly 40% in the 1990s. The rest are functionally decided in low-turnout party primaries.
In safe seats, the only electoral threat comes from primary challengers. This incentivizes incumbents to adopt more extreme positions to satisfy their base, while ignoring the median voter entirely.
An estimated 49 million votes cast in the 2020 House elections were effectively wasted — either piled onto landslide victories or spent on hopeless losses by design.
In 2022, Republicans won 54% of House seats on 52% of the vote. Democrats won 46% of seats on 48% of votes. Under fair maps, the split would be roughly 50-50.
Gerrymandering has been legally sanctioned, technologically supercharged, and politically weaponized. Lawsuits haven't stopped it. Outrage hasn't stopped it. Understanding gerrymandering is the first step. The second is demanding change.