FLASHCARDS: Gerrymandering and the Math Behind the Maps

🔎 Episode Overview
In this episode of Math, Science, History, we explore one of the most quietly powerful forces in American democracy: gerrymandering. From its origin over 200 years ago to its impact on today’s elections, gerrymandering is both a political weapon and a mathematical puzzle.

We break down the mathematical principles used to detect gerrymandering, explore real court cases in Southern states, and examine how computer science and voter data are used to both draw and fight unfair districts. You’ll also learn how other countries handle redistricting—and what the U.S. can learn from them.

Whether you're a math geek, a science lover, or just a concerned citizen, this episode gives you practical tools and knowledge to take action against one of the most manipulative practices in modern politics.

✅ 3 Things You Can Do to Stop Gerrymandering

-          Support Independent Redistricting Commissions
Advocate for fair districting in your state by supporting or starting initiatives to create nonpartisan redistricting commissions.

-          Use Data Tools to Analyze Your District
Explore your voting maps using free tools like .css-j9qmi7{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-flex-direction:row;-ms-flex-direction:row;flex-direction:row;font-weight:700;margin-bottom:1rem;margin-top:2.8rem;width:100%;-webkit-box-pack:start;-ms-flex-pack:start;-webkit-justify-content:start;justify-content:start;padding-left:5rem;}@media only screen and (max-width: 599px){.css-j9qmi7{padding-left:0;-webkit-box-pack:center;-ms-flex-pack:center;-webkit-justify-content:center;justify-content:center;}}.css-j9qmi7 svg{fill:#27292D;}.css-j9qmi7 .eagfbvw0{-webkit-align-items:center;-webkit-box-align:center;-ms-flex-align:center;align-items:center;color:#27292D;}

Episode Transcript

(00:02):
(Transcribed by TurboScribe.ai. Go Unlimited to remove this message.) Welcome to Flashcard Fridays here at Math Science History, and today I'm going
to be talking about a topic that is as mathematical as it is political.
Gerrymandering.
It's a practice that has shaped American democracy for over 200 years,
influencing elections, power, and representation.

(00:22):
But did you know that math and science are key tools in both creating and
fighting gerrymandering?
Today I'm going to explore the history, the mathematical constructs behind it,
and how people can take action to create fair elections.
Before I break down the math and science behind it, I'm going to define
gerrymandering.
It's the practice of manipulating the boundaries of electoral districts to

(00:46):
favor one political party over another.
And I love this story.
It gets its name from Elbridge Gerry, a governor of Massachusetts who, in 1812,
approved a district shaped like a salamander.
A political cartoonist dubbed it a gerrymander, and the name stuck.
Today it remains a major tool for political parties to control elections.

(01:11):
Gerrymandering is nearly as old as American democracy itself.
In the 19th century, politicians redrew maps to weaken opponents.
However, in the 20th century, redistricting became more precise, with
politicians using census data to suppress certain voting blocs.
After the Voting Rights Act of 1965, racial gerrymandering became more

(01:33):
scrutinized, but partisan gerrymandering persisted.
In 2019, the Supreme Court ruled in Rucho v.
Common Cause that federal courts cannot decide cases on partisan
gerrymandering, making state action more important than ever.
Now let's talk numbers.
Gerrymandering relies heavily on mathematical principles.

(01:55):
One of the simplest ways to measure gerrymandering is by looking at
compactness.
A district should ideally be as compact as possible, but gerrymandered
districts are often oddly shaped.
Scientists use different mathematical tests to measure this, such as the
Polsby-Popper score.
This is a ratio comparing a district's area to the area of a perfect circle.

(02:20):
The closer to one, the more compact.
The closer to zero, the more suspicious.
The Schwartzberg ratio compares the perimeter of a district to a circle's
perimeter of the same area.
And the Reock score, which measures how much of a district's area fits within
the smallest possible circle around it.
So I'm going to provide an example.

(02:41):
North Carolina's old 12th congressional district once had a Polsby-Popper
score of just .017. This was a clear indication that it was manipulated.
So there are two main strategies used in gerrymandering.
These include packing and cracking.
Packing is when they concentrate opposition voters into one or a few districts,

(03:03):
wasting their votes.
Cracking spreads opposition voters across multiple districts, diluting their
voting power.
For example, imagine a state with 60% Democrats and 40% Republicans.
In a fair map, districts would reflect that ratio.
But with gerrymandering, districts could be drawn so that Republicans control

(03:24):
most of the seats, despite being the minority.
That's the power of mathematical manipulation in politics.
So here's the science behind gerrymandering.
Beyond math, computer science has revolutionized gerrymandering.
Political map makers use machine learning and data modeling to draw maps that
favor their party.
These algorithms use demographic data, voter history, and even social media

(03:48):
trends to predict how people will vote.
But the same technology is being used to fight gerrymandering.
Researchers at Princeton and Harvard have developed automated redistricting
algorithms to create fair maps.
These computer-generated maps serve as a benchmark to determine whether
official maps are extreme outliers.

(04:08):
So let's look at some of the most notorious gerrymandering cases.
Okay, Gomillion v.
Lightfoot.
This was in 1960 in Alabama.
Alabama redrew the city of Tuskegee's map to exclude nearly all black voters.
The Supreme Court ruled this was unconstitutional racial gerrymandering.
Shaw v.
Reno in 1993 in North Carolina.

(04:31):
The court ruled that race-based districting is unconstitutional unless there is
a compelling reason.
Abbott v.
Perez in 2018 in Texas.
Texas was found to have drawn maps that discriminated against Latino voters.
Allen v.
Milligan in 2023 in Alabama.
The Supreme Court ruled that Alabama's congressional map violated the Voting

(04:55):
Rights Act diluting black voters' influence.
Each of these cases highlights how gerrymandering affects real communities.
Gerrymandering isn't just a problem in the United States either.
In the United Kingdom, the UK has an independent boundary commission that
redraws district lines every 8 to 12 years, reducing political interference.

(05:19):
Canada also uses independent commissions, a reform that ended past
gerrymandering practices.
Australia.
Australia's independent electoral commissions prevent gerrymandering, though
malapportionment used to favor rural areas.
India.
India's delimitation commission is meant to be independent, but political

(05:41):
influence still plays a role.
And Russia.
While Russia doesn't rely on gerrymandering in the same way, other forms of
electoral manipulation like voter suppression take place.
But many democracies have independent commissions to ensure fair redistricting,
something that some U.S. states are beginning to adopt, like in states like

(06:02):
California and Colorado.
So how can we fight gerrymandering?
Gerrymandering may seem overwhelming, but there are ways to fight back.
One, support independent redistricting commissions.
States like Michigan and California have successfully removed politicians from
the map-drawing process.

(06:23):
Two, push for state-level legal challenges.
Some state Supreme Courts, like Pennsylvania's, have struck down unfair maps.
Three, support federal legislation.
Bills like For the People Act, which is H.R. 1, and the John Lewis
Voting Rights Act could establish national protections.

(06:44):
Number four, use data and technology.
Tools like Dave's Redistricting App and PlanScore allow voters to analyze
district maps.
Five, vote in state elections.
Since state legislators control redistricting, voting in these elections is
crucial.

(07:04):
Six, advocate for ballot initiatives.
In states that allow it, pushing for redistricting reform via ballot measures
can be an effective strategy.
Also, organizations like Common Cause and the Brennan Center for Justice are
working to fight gerrymandering.
Getting involved or donating can make a big difference.

(07:26):
Finally, gerrymandering is a political problem, but math and science provide
the tools to expose and fix it.
While politicians may try to manipulate district lines, voters, activists, and
researchers have the power to fight back.
It takes awareness, advocacy, and participation at all levels of government.

(07:50):
Thank you for tuning in to Flashcard Fridays at Math, Science, History, and
until next time, carpe diem.