A group of SMU mathematicians and one philosopher are using math to measure how biased voting district maps are in Texas.
The group, called Math for Unbiased Maps TX, uses software that generates millions of maps to compare with proposed district maps, creating an opportunity for greater accountability in redistricting.
Every 10 years, after the U.S. census, states use data on race, Hispanic origin and the voting-age population to redraw the boundaries of their congressional and state legislative districts.
In Texas, Republicans control the redistricting process because of their majorities in the House and the Senate.
Legislators use gerrymandering, or the practice of dividing election districts in a way that gives one political party an advantage, to manipulate these maps. This practice has been used by U.S. politicians for about as long as our country has existed.
But just how biased have modern-day maps become in the state of Texas? The map that was approved last October is so highly biased, it is quite literally off the charts, according to the SMU findings.
The open-source software that the SMU researchers use helps them generate millions of maps that follow state guidelines for drawing districts.
The software allowed the researchers to answer a simple question: “If you didn’t try to design [maps] to maximize Democratic seats or Republican seats, if you just pick them randomly to satisfy the law — what would you get?” said Andrea Barreiro, associate professor of mathematics at SMU.
Using this large set of randomly generated maps, the group established a baseline for what a typical map that follows state guidelines looks like. With this baseline, the researchers were then able to measure how far from the baseline a proposed map was — and, therefore, how biased it was.
“If you have something that’s way outside of [the baseline], then there must have been some design goal that pushed it away from all these randomly generated maps, and that’s what we would call a biased map,” said Scott Norris, SMU associate professor of mathematics.
As soon as Texas’ first proposed congressional maps were made available on the Capitol Data Portal in late September, the SMU team got to work analyzing how the maps fared.
As different maps were proposed, the team generated over a million maps to create an unbiased baseline, offering key measures that are commonly used by political scientists to assess gerrymandering.
They completed this analysis for 59 proposed congressional maps. (The SMU team also shared their analysis for proposed Texas House, Senate and city council maps.)
Of the 1.5 million maps that the team generated and analyzed to compare with the final proposed Texas congressional district map, not a single baseline map showed levels of bias as high.
The proposed map was more biased than every single map their software had generated, the SMU researchers showed.
With their findings in hand, the SMU team reached out to all members of the Texas subcommittees involved in redistricting, as well as the researchers’ own local legislators.
They sent emails and posted to the comment portals provided by the legislature. Several of them testified at an open community hearing, explaining how this software works and advocating for its use to create less biased maps.
But they only heard back from a few offices. “The only people that we have actually spoken to are Democrats. … As you might expect, we haven’t had any interest from Republican members of the committees and, you know, that makes sense from their perspective,” said Norris.
On Oct. 25, 2021, the map was signed into law by Gov. Greg Abbott, cementing the likely power of Republicans in the state for the next 10 years.
So, how could this affect voters? One of the consequences of gerrymandering is that certain districts become less competitive — meaning that the party benefiting from gerrymandering can win more seats without having to earn more votes.
“What gerrymandering really is, is putting your thumb on the scale to engineer a result that you like, to the detriment of people that you don’t like, whether that’s people of a different political party or people of a different race,” said Michael Li, senior counsel for the democracy program at the Brennan Center for Justice at New York University School of Law. He is not involved or affiliated with the SMU research group.
Gerrymandering “defeats the fundamental goal of representation that the founding generation had,” he said.
The SMU group’s software revealed that the approved Texas map reduced the competitiveness of almost 50% of congressional districts in the state. This means that Republicans can win 50% of the state’s congressional seats, with only 42.2% of the state’s votes, the researchers showed.
In addition to dampening the need for officials to earn votes, gerrymandering can also leave large numbers of voters in a district with a representative who is out of touch with their community, said SMU researchers.
“When we testified to the House about this, I was struck [by] how many rural Republican voters were basically pleading with legislators not to break up their districts,” said Matthew Lockard, SMU associate professor of philosophy.
Farmers worried that their lives are so different from those of the city voters they might be in a district with that it just didn’t make sense.
But political gerrymandering is not the only type of gerrymandering with a long history in the U.S. Racially motivated gerrymandering has long been used to dampen the voices of minority voters.
“That reluctance to give Black and Latino communities a seat at the table — that was the case when Democrats were in control of line drawing in the ‘70s and ‘80s, and it is true when Republicans are in control of line drawing today,” said Li.
Tools like the one used by the SMU researchers offer greater accountability to the redistricting process. But the impact is blunted without the will to actually use these tools, experts said.
And as the centuries-long legacy of gerrymandering shows us, the status quo is an unassuming, but powerful, force.
Fighting gerrymandering is not a high priority for most voters, and it’s a challenge for citizens to get involved because the process is complicated and moves so quickly, said Matthew Wilson, an SMU associate professor of political science who consulted with the SMU researchers.
But for voters who do want to get involved with their state’s redistricting process, Li offers some hope. The issue of gerrymandering “resonates with enough people that there is the ability to shine a light on it and make it harder for people to do. Because they depend on everything happening in the dark for it to be successful,” said Li. “Like anything else, it’s a matter of organizing,”
Jessica Rodriguez reports on science for The Dallas Morning News as part of a fellowship with the American Association for the Advancement of Science.
