A big question looming over future redistricting: Who should count?

The impacts of the latest fight over Texas’ political maps are still reverberating around the state, but there are other debates on the horizon.

Future political representation could hinge on President Donald Trump’s renewed push to exclude at least some noncitizens from the population counts that help determine how political power is distributed in the U.S.

In Texas, where Republicans pushed through a rare midcycle redistricting this year to try to maintain their advantage in Congress after the 2026 midterm elections, experts say that excluding noncitizens when drawing districts could open another way for the GOP to tighten its grip on the state Legislature and congressional delegation.

In addition, many experts and critics worry it could ultimately place some Texas communities into larger, less cohesive districts, while diluting the political influence of Latinos and other minority groups who have accounted for much of the state’s population gain in recent decades. Adding questions about citizenship to the U.S. census could also lead to more undercounting of Latinos, they warn, a problem that has plagued previous censuses.

The various proposals raise substantial undecided legal and constitutional questions that would have to be settled in court, making the outcomes of such changes impossible to precisely predict. But to understand the possibilities if some or any of these proposals go forward, it’s helpful to separate them into three categories: changes to the census; changes to the apportionment of House seats and electoral votes among states; and changes to the drawing of congressional and state legislative districts, which happens at the state level.

How we count people — and which people count

Any effort to reanchor the distribution of political power around citizenship starts with the decennial census. Republicans and conservative groups are lining up behind a continuing effort to add a citizenship question to the questionnaire, a plan that ran into legal hurdles during the first Trump administration.

Under the Constitution, the decennial census — “counting the whole number of persons in each State” every 10 years — determines how many congressional representatives and electoral votes each state gets. As courts have interpreted this clause in the past, it means everyone is counted, regardless of their age, immigration or citizenship status, or eligibility to vote.

Trump has pushed this year for a new, mid-decade census that would not count immigrants without legal status. But the census has a long lead time. The Census Bureau says it’s been preparing for the 2030 census since 2019 and is planning to conduct a major on-the-ground test for it in 2026. The commerce secretary must submit census questions to Congress two years before the actual census takes place.

There are also several Republican-supported bills that would affect the census’s counting of noncitizens. They differ, but they generally call for using only the number of U.S. citizens, rather than the total population, to calculate how to apportion House seats and electoral votes among the states. Four Republican-led states earlier this year also sued the federal government, arguing that undocumented immigrants and immigrants with temporary visas shouldn’t be included, though that case has been stayed for now.

Some Republicans who support the proposals argue that including noncitizens creates imbalances in citizens’ voting power depending on where they live — rewarding jurisdictions that welcome undocumented immigrants. “Today, a voter in a congressional district with 730,000 citizens … and 30,000 illegal aliens has a stronger say in the election of his representative than a voter in a congressional district with 760,000 citizens and no illegal immigrants,” U.S. Rep. Chip Roy, a Texas Republican, said during a congressional committee hearing on the census in November.

Democrats, meanwhile, said the proposals would be unconstitutional and would hurt vulnerable populations.

“Alexander Hamilton is on record saying during the Constitutional Convention in Philadelphia, ‘There can be no truer principle than this: that every individual of the community at large has an equal right to the protection of the government,’” said U.S. Rep. Mary Gay Scanlon, a Pennsylvania Democrat. “Ultimately, the census is a national snapshot we take every 10 years that helps us understand and define who we are, how to govern, and undermining that process in ways that distort that picture will harm all of us.”

If all or some noncitizens were to be excluded from the census, states estimated to have large populations of noncitizens — a red and blue mix that includes Texas, California, New Jersey, Florida, and New York — could lose House seats and electoral votes, or gain fewer than they would have.

But multiple legal experts, including Justin Levitt, a constitutional law expert and professor at Loyola Law School who advised President Joe Biden’s administration on democracy and voting rights, and Michael Morley, a law professor at Florida State University’s College of Law and an expert on election and constitutional law and voting rights, say excluding all or some noncitizens from apportionment counts would be unconstitutional, given the clear language on apportionment in the Constitution’s 14th Amendment. It would quickly draw legal challenges, and they don’t believe courts would allow it, they said.

But if the Trump administration adds a census question on citizenship, which wouldn’t in itself change the apportionment counts, that would generate the key data state officials would need to draw their internal U.S. House and state legislative district lines based on the population of citizens.

In a 2016 case over state-level redistricting in Texas, the U.S. Supreme Court left open the question of whether states could use criteria other than total population, such as the population of eligible voters — roughly speaking, citizens age 18 or above — for the state-level task of drawing district maps. Texas, according to the court’s ruling in Evenwel v. Abbott, had argued that “jurisdictions may, consistent with the Equal Protection Clause, design districts using any population baseline—including total population and voter-eligible population—so long as the choice is rational and not invidiously discriminatory.”

Experts disagree, however, on whether the Supreme Court has left the question open for both congressional districts and state legislative districts or just for state legislative districts. Morley, for example, said the former, while Levitt believes the latter.

During the failed push to add a citizenship question to the 2020 census, evidence emerged showing a longtime political strategist had drawn up a case study showing that using the population of voting-age citizens rather than total population to draw Texas state House districts would advantage Republicans and non-Hispanic white Texans. That’s a big reason why some experts and advocates are concerned about the implications for communities of color.

If Texas draws districts to have equal populations of adult citizens rather than equal total populations, some districts would have to grow geographically to include enough adult citizens — creating districts that are larger geographically and by total population. The effects of using citizen voting-age population would likely be most pronounced in the Dallas-Fort Worth and Houston areas and in the Rio Grande Valley, according to experts and an analysis by the Electoral Innovation Lab done earlier this year for Votebeat.

The effect will “tend to be to shift power away from urban areas that have larger numbers of noncitizens,” Morley said.

In these districts, U.S. citizens would see an impact as well. Individuals would have less representation if everyone isn’t counted, said Jonathan Cervas, a redistricting expert, assistant teaching professor at Carnegie Mellon University, and collaborator with the Electoral Innovation Lab.

“That’s the real-world consequence” of redistricting based on citizen-only population counts in those areas, he said. Actual citizens “end up worse off.”

How a citizens-only count would affect redistricting

Let’s look at an example: The Rio Grande Valley

The Rio Grande Valley is one of the areas where new political boundaries based on citizenship voting-age population could have a profound effect, according to the analysis by Cervas, Neil Dixit, and Sam Wang of the Electoral Innovation Lab, as well as other redistricting experts.

Near the eastern end of the Texas-Mexico border, neighboring Hidalgo and Cameron counties are home to more than 1 million people combined. The area has a diverse population that works in manufacturing, agriculture, healthcare, retail, and food service industries.

Both counties also have multiple ports of entry between Mexico and the U.S., overwhelmingly Latino populations, and many mixed-status households.

The area is also home to more than 1,000 colonias — unincorporated rural communities that often lack access to basic services and infrastructure — housing anywhere from two dozen to over a thousand each.

The area is part of the Democratic-leaning 34th Congressional District, which, as it stands now, includes eastern Hidalgo County and all of Cameron, Kenedy, Kleberg, and Willacy counties. (The map state lawmakers passed this summer takes the Hidalgo County part of the district out and instead adds part of Nueces County.)

If the district had to be redrawn based on its citizen voting-age population, it would almost certainly need to grow geographically, according to an analysis by Cervas, because otherwise there wouldn’t be enough citizens in it to keep it equal to other districts.

Lupita Sanchez, a resident of Brownsville in Cameron County and executive director of Border Workers United, a nonpartisan immigrant advocacy nonprofit, said redistricting should be fair. “Everyone should be counted because everyone contributes to this nation in different ways,” she said.

Why the census citizenship question matters

The first Trump administration fell short in its push to add a citizenship question to the 2020 census. The U.S. Supreme Court ruled that the administration’s stated reasons for wanting to add the question were contrived — but it didn’t preclude asking it on a future census.

Aside from apportionment and redistricting, census data helps inform how trillions of dollars in funding are allocated to states to improve health, housing, education, and other community services. It helps businesses plan investments and local governments decide how to allocate resources, such as services for the elderly and where to build new roads, schools, or job training centers. So the developers of the census questionnaire strive to tread lightly with any change that might diminish response rates or compromise the completeness of the data they collect.

Census questionnaires are distributed to individual addresses and capture answers about everyone in the household. Even though the answers are not released to the public and are used only to generate statistics, experts have long said that adding a citizenship question would make some people, especially immigrants, less likely to respond to the census, resulting in less accurate data and further diminishing the political influence of some communities.

The Republican push to add a citizenship question “is designed to deepen the distrust and therefore trigger an even higher undercount, specifically of the Latino community,” said Thomas Saenz, president and general counsel at the Mexican American Legal Defense and Educational Fund, which opposed the first Trump administration’s 2020 effort.

“Mistrust runs deep,” said Victoria Fajardo, a resident of Hidalgo County in the Rio Grande Valley and a community advocate with the immigrant and social services advocacy group La Union del Pueblo Entero (LUPE). That’s especially true in “mixed-status households” — families with U.S. citizens and noncitizens, including legal permanent residents and undocumented immigrants, under one roof. Around 8% of Texas households include an undocumented immigrant, according to Pew Research Center estimates from 2022.

People fear their personal information could be shared with government agencies for enforcement reasons, Fajardo said. Adding a citizenship question to the census “would just further the undercounting of the community. Especially under this administration,” she said, “where it feels like surveillance of immigrants is heightened.”

The census has already undercounted the population in parts of the Rio Grande Valley in the past, advocates say.

Prominent Texas officials supported Trump’s effort to add the citizenship question to the 2020 census, and Texas also joined a multistate brief filed with the Supreme Court in favor of the Trump administration’s position. In 2019, Texas Gov. Greg Abbott said the idea that it would lead to an undercount was “nothing other than conjecture.”

How redistricting is supposed to work

Each state’s political maps must be redrawn once per decade, after each census, to account for population growth and ensure that every congressional or legislative district has virtually the same number of people. Mid-decade redistricting, like the one Texas pushed through this year, is legal but unusual — although Trump’s push to add red seats in some states has set off a chain reaction of it this year.

In Texas and most other states, redistricting is the purview of the state legislature and governor, and if one party controls both, it can draw the boundaries for both congressional districts and state legislative districts as it sees fit. Within certain limits, state lawmakers can effectively decide which voters they want in each district, based on political or partisan objectives. The practice goes back centuries, but modern data tools have made it easier to precisely draw boundaries that include or exclude certain voters and maximize partisan advantage.

In other states, it’s up to a bipartisan or independent commission to oversee redistricting.

There are a few rules and principles that apply in all states. For example, a given state’s districts must have virtually equal populations. All states must comply with the 14th Amendment to the Constitution and the Voting Rights Act, which means they can’t discriminate on the basis of race — though a U.S. Supreme Court decision is pending in a case out of Louisiana that could drastically change how the Voting Rights Act applies to redistricting.

There are also widely applied redistricting principles that call for districts to be, among other things, compact and contiguous and to preserve communities of interest and follow other lines, such as city boundaries, whenever possible. And several states have specific requirements of their own: In Texas, for example, lawmakers must also comply with the state constitution’s requirements when it comes to splitting counties between state House districts.

Courts have found Texas’ congressional maps to be racially gerrymandered in every decade from the 1970s to the 2010s.

The maps that Texas Republicans drew after the 2020 census were under challenge in court when lawmakers decided to redraw the state’s congressional map this summer, though judges had yet to rule. The new map was promptly challenged in court as well, and in November, a panel of federal judges struck down the map as a racial gerrymander. However, their decision was appealed to the U.S. Supreme Court, which ruled Dec. 4 that Texas could use its new congressional map while the high court considers the merits of the case. That makes it likely that the congressional map lawmakers passed this summer will be used in the 2026 election.

Natalia Contreras is a reporter for Votebeat in partnership with The Texas Tribune. She is based in Corpus Christi. Contact Natalia at ncontreras@votebeat.org.