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SMU researchers say Texas lawmakers’ redistricting maps show clear bias toward Republicans


Math for Unbiased Maps created 1.5 million random redistricting maps and none were as biased as the one lawmakers approved

Researchers at Southern Methodist University say new congressional maps passed by Texas lawmakers are significantly biased and engineered to create a Republican advantage.

Andrea Barreiro is an associate professor of mathematics at SMU and part of the group Math for Unbiased Maps. She says the group produced 1.5 million random maps based on rules for redistricting like similar populations and keeping districts contiguous.

The legislature’s passed map, though, was far beyond even the most extremely biased map from the 1.5 million.

“We were actually kind of shocked and we felt a little angry I think,” Barreiro said. “It was very clearly biased.”

Math for Unbiased Maps started last spring to study redistricting using what’s known as Markov Chain Monte Carlo (MCMC) method for guiding a random search. The goal was to see how much the maps were gerrymandered, where they’re purposefully set to give one party an advantage.

“We wanted fair maps as voters and as citizens,” she said.

Redistricting only happens every 10 years when new census data is released. This year, Texas added two congressional seats and Barreiro says there are likely billions of ways to carve up the state even bound by legal map-making guidelines.

Census data shows 95% of Texas’ growth is communities of color that vote Democratic. That includes 1.9 million new Hispanic residents, nearly 10 times the number of non-Hispanic white residents added to the state.

“It will determine the shape of power for the whole of the decade,” Michael Li, senior counsel at NYU’s Brennan Center, told WFAA last fall. “It is something that is challenging, but I like to call redistricting an every-10-year Olympics.”

Li said Texas has been flagged before and faced legal challenges over intentional discrimination.

They tested both the new state senate district map and congressional districts. The 1.5 million maps created gave them a baseline to work from.

The median model would give Democrats a two-district advantage, but the maps approved instead gave Republicans a 12-district edge.

“Excessive political gerrymandering harms the voter,” Barreiro said. “it makes races less competitive. It privileges one political party over another. It can privilege one racial group over another.” READ MORE