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The Curse of Gerrymandering — & the Mapping Software Behind It

First, for those of you who are not accustomed to the ‘American Way’, a short introduction to gerrymandering:

The term is used to describe adjusting voting district boundaries to create an unfair advantage for a particular party or group. Basically it’s a way to enable a minority of the population to win control of government. 

The term gerrymandering is named after the American politician Elbridge Gerry who was the 5th vice president of the USA under president James Madison from March 1813 until his death in 1814. Prior to becoming vice president Gerry was the governor of Massachusetts. 

Elbridge Gerry – Credit: Wikimedia

In 1812, while Gerry was governor, the Jeffersonian Republicans forced a bill through the Massachusetts legislature to rearrange voting district lines to assure them an advantage in the upcoming senatorial elections. Apparently Governor Gerry only reluctantly signed the law.  One of the districts was compared to the shape of a salamander, but when a particularly influential editor at the time saw it, he is said to have exclaimed: “Salamander! Call it a Gerrymander!” 

As a result a cartoon-map depicting this district appeared in the Boston Gazette on March 26, 1812:

“The Gerrymander: a New Species of Monster” Boston Gazette, March 26, 1812, Credit -Library of Congress. 

Ever since the term has had a negative connotation — indicating corruption of the political process. 

So how does this nefarious process of gerrymandering work?  Well let’s look at a simple example:

When creating voting districts there are certain basic rules put in place that prevent overtly egregious boundaries. For example, it is common to require that each district have  equal population, thereby preventing the voters in one district having more influence than another. For US Congressional Voting Districts the variation in population is generally held to less than 1%.  Obviously populations change over time and so countries use information gained from a national census as input to redraw the boundaries. In the US this happens every 10 years. 

Continuing with a hypothetical example, let’s imagine that the requirement is to create 5 voting districts from a set of 50 precincts. Let’s assume each precinct has equal population. More importantly let’s assume we know the voting characteristics of each precinct — i.e. whether the voters in each precinct would vote for the ‘Purple’ party or whether they would vote for the ‘Orange’ party. Given these assumptions here are two different ways to draw the boundaries that result in entirely different outcomes:

If you think this is all rather academic and can’t possibly happen take a look at some of these contortions in 2022 US Congressional Districts. Now, I’m not saying that contortion implies gerrymandering, but it sure looks weird to me. And sorry @Texas — you win the prize for the most convoluted shapes:

[Huge credit to Alasdair Rae for providing the maps above. Alasdair is an internationally recognized mapmaker, data analyst, author and visual storyteller. Formerly a Professor of Urban Studies and Planning in the UK, he now runs Automatic Knowledge, a UK-based data, analysis and training company.]

What’s worse is attempts to create disproportionate outcomes based on race. The site All About Redistricting,  is a great resource to learn more about the whole redistricting process. It has this to say about the various ploys used to achieve discrimination:

In redistricting, one ploy is called “cracking“: splintering minority populations into small pieces across several districts, so that a big group ends up with a very little chance to impact any single election. Another tactic is called “packing“: pushing as many minority voters as possible into a few super-concentrated districts, and draining the population’s voting power from anywhere else.

In the US discrimination like this is in theory prevented by Section 2 of the 1965 Voting Rights Act. However, this may all be upended in a new case being considered by the current session of the US Supreme Court, Merrill vs. Milligan. The London Guardian wrote about the case just a few days ago

Merrill v Milligan concerns Alabama, where Republican lawmakers want to draw up congressional district maps that would give Black voters the power to send just one African American member to Congress out of a total of seven representatives, even though Black Alabamans make up a quarter of the state’s population. The map was blocked by three federal judges who ruled that it was racially discriminatory and that the state had engaged in racial gerrymandering.

In its brief to the supreme court, Alabama effectively invites the conservative justices to make it virtually impossible to challenge racial gerrymandering. Should the state’s view prevail, challengers would have to show that racial discrimination was the primary intent behind how district lines were drawn.

“That’s a very hard standard to prove,” said Paul Smith, senior vice-president of the Campaign Legal Center. Should the supreme court side with Alabama, Smith added, “it would allow legislatures to undo Black and Latino-majority districts and do away with the opportunity of people to elect their own representatives”.

The case was argued before the Supreme Court on October 4. It will be some months before the outcome is known. 

So, given all this, how exactly does one go about creating voting districts in the first place? It must have been incredibly laborious to do it all by hand back in the days of Elbridge Gerry. Today of course we have technology at hand — and not just any technology — we have mapping technology!

According to Ballotpedia there are six packages designed for specifically governments1:

Software PackageDeveloperBackend Technology
AutoboundCitygate GISEsri ArcGIS
Esri RedistrictingEsriEsri ArcGIS
Maptitude for RedistrictingCaliperCaliper
Credit: Information from Ballotpedia

I was fully expecting the websites for these products to be emblazoned with colorful ads, perhaps something like this: 

Alas — they are all quite boring and only talk about how they can be used to help in creating plans that “meet legislative requirements”. However, I have no doubt that any of these tools could be misused. One other note: none of them mention AI or ML. No doubt that’s coming though. I can only imagine what it will bring.

So is gerrymandering just a phenomenon limited to the US? And what can be done to prevent it? 

Canada is one example where gerrymandering was rife until the 1960s. Andrew Prokop writes about it in his article on Vox: “How Canada ended gerrymandering”. Andrew explains what Canada did:

“Canadian reapportionment was highly partisan from the beginning until the 1960s,” writes Charles Paul Hoffman in the Manitoba Law Journal. This “led to frequent denunciations by the media and opposition parties. Every 10 years, editorial writers would condemn the crass gerrymanders that had resulted.

Eventually, in 1955, one province — Manitoba — decided to experiment, and handed over the redistricting process to an independent commission. Its members were the province’s chief justice, its chief electoral officer, and the University of Manitoba president. The new policy became popular, and within a decade, it was backed by both major national parties, and signed into law.

Independent commissions now handle the redistricting in every province. “Today, most Canadian ridings [districts] are simple and uncontroversial, chunky and geometric, and usually conform to the vague borders of some existing geographic / civic region knowable to the average citizen who lives there,” writes JJ McCullough.

“Of the many matters Canadians have cause to grieve their government for, corrupt redistricting is not one of them.” Hoffman concurs, writing, “The commissions have been largely successful since their implementation.”

Implementing independent, nonpartisan commissions in the US is more complex. The decision is made at the state level, not the federal level. And I guess certain states (both Democratic and Republican) are perfectly happy to have the fox guard the hen house. 

Again from Andrew’s article:

”There are no truly nonpartisan redistricting commissions in the United States,” political scientist Bruce Cain of Stanford University told me in 2014. Iowa uses a nonpartisan agency that’s not permitted to take party registration into account, but it still gives final say to the governor and legislature.

If all this leaves you rather depressed there is one ray of hope. A recent report by David Leonhardt in the New York Times “finds that the House of Representatives has its fairest map in 40 years, despite recent gerrymandering”. 

I’ll leave you with a quote from Bernard Grofman and German Feierherd in a Washington Post article from 2017:

However, in most other countries, legal challenges [to voting districts] are limited, and there is not the same concern for strict population equality.

So perhaps the problem all boils down to lawyers?  Ah, but then that’s a whole other topic, isn’t it?


1 There are other packages but they are designed more for the general public and educational purposes.


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