Whether fast-growing Texas suburbs can shape next week's U.S. Senate election depends not only on how many people live there, but also on how many are registered and how they vote. Over the past decade, these counties have grown and diversified, while their voting patterns have differed from those of the state as a whole.
The Texas Tribune's analysis covers 16 counties it classifies as suburban, based on population, metropolitan classification and density criteria, according to The Texas Tribune. The definition includes large fringe metro counties with at least 50,000 residents and a city or part of a city with at least 25,000 residents, while excluding suburban portions of urban counties like Harris and Dallas. Collin County, despite its large central metro classification, is included; its population is now nearly 1.2 million. Smaller counties like Rockwall and Hunt have between 120,000 and 145,000 residents.
The Tribune reports that these 16 counties' share of Texas registered voters rose from about one-fifth to nearly one-quarter over eight years. Each county recorded at least 30% more registered voters in 2024 than in 2012; Comal County had the largest increase, at 83%. How those voters cast ballots could affect the Senate contest and legislative races across the state.
Population Growth Across Regions
Collin County, north of Dallas, added almost 43,000 new residents between July 2024 and July 2025, according to KXAN, with 83% of that growth coming from people moving in from elsewhere rather than births. Statewide, Texas grew by 391,243 people over that same year, and Kaufman County ranked among the 10 fastest-growing counties in the entire country, expanding 5.67% in a single year.
Hays and Williamson counties have both grown by more than 23% between 2020 and 2025, placing them among the state's fastest-growing places, per the same Tribune analysis. Galveston County posted the slowest growth among the 16 suburban counties at 21%. Much of the newer growth in Dallas-Fort Worth suburbs is arriving from out of state — six of the top ten out-of-state origin counties for new arrivals were in California, with Phoenix, Chicago, Seattle and Las Vegas also serving as major points of origin.
What Growth Figures Can—and Can't—Tell Us
The suburban county figures do not by themselves show how much of the rise in registered voters came from population growth and how much from changes in registration rates. Statewide, the Houston Chronicle reports that since 2005, Texas's population has grown by just over a third while registered voters increased by about half. That comparison suggests registration has grown faster than population statewide.
A Diversifying Electorate
The Tribune's analysis found that people of color accounted for 40% of the population in the 16 counties in 2014 and nearly half in 2024, with the counties diversifying almost twice as fast as the rest of Texas. In Collin and Fort Bend counties, Asian residents now make up between 22% and 24% of the population. In Hays and Williamson counties, the white population share fell below 50% between 2020 and 2025.
That diversification hasn't translated into uniform political movement. Republicans have made gains with Indian American and Asian voters broadly, the Tribune reports, which has slowed the leftward shift in Collin and Fort Bend in 2024 even as those counties continue to diversify.
A Mixed Electoral Picture
The Tribune's review of Senate results shows a different trajectory in the suburbs than in Texas overall. Ted Cruz won the 16 counties by 33 percentage points in 2012; that margin narrowed to 15 points in 2018. In 2024, Cruz improved his statewide margin by six points over 2018.
The counties' electoral patterns varied between 2012 and 2024. Kamala Harris outperformed Hillary Clinton in 14 of the 16 suburban counties between 2016 and 2024. Fort Bend County voted for a Democratic Senate candidate in 2018 for the first time in 30 years and has done so in every Senate contest since.
Not every suburb moved the same direction. Irving shifted more than 15 percentage points toward Republicans between 2020 and 2024, according to VoteHub data cited by the Tribune, while Plano shifted a more modest 6 points rightward over the same period. Midlothian, meanwhile, shifted nearly 9 points toward Democrats between 2020 and 2024 even as it continued to vote solidly Republican overall.
Montgomery County remains a Republican stronghold and gave Donald Trump the largest raw-vote margin of any county in the country in 2024.
Migration and Voting Patterns
Who is moving into these counties — and where they're coming from — appears to matter. CNN found that Beto O'Rourke narrowly won native Texans in 2018 while Cruz dominated among people who had moved to the state. That pattern held in 2024: Allred won Texas-born voters by 4 percentage points, while Cruz won Texas transplants by 16 points, according to CNN's analysis.
Jill Tate, president of the Texas Federation of Republican Women, told the Tribune that people moving from other states tend to want Texas to remain as it is, while some long-time residents are pushing for change. Wayne Thorburn, who served as executive director of the Republican Party of Texas from 1977 to 1983, said Trump has lost some voters who once identified with a Republican Party built around upwardly mobile younger voters.
Legislative Seats
The suburbs have produced some of the state's most prominent political careers. Ken Paxton first won elected office representing a suburban state legislative seat in McKinney in 2002, while James Talarico first won elected office representing a suburban seat in Round Rock in 2018 — the same year Democrats flipped six suburban-area Texas House seats. Texas House district boundaries were redrawn in 2023, reshaping some of those same battlegrounds.
Barry Jacobs, a 62-year-old attorney in Waxahachie, embodies the suburban swing voter the data describes. He voted for Cruz in 2018, backed Colin Allred in 2024, and now plans to vote for Talarico in 2026.
Precinct Results and the Statewide Stakes
The precinct-level picture from 2024 underscores how much suburban turnout can shape statewide results. Cruz won the most votes in 5,040 Texas precincts in the 2024 Senate election, compared with 4,277 precincts won by Allred, according to KXAN. Allred's strongest precinct-level margins were concentrated in larger cities, including Austin, Dallas, Houston and San Antonio, rather than the suburban counties themselves. VoteHub, whose precinct model underpins some of this analysis, cautions that precincts with small populations may produce imprecise results.
With registered voters in the 16 counties approaching a quarter of the state's total, their continued growth makes the suburbs an important part of the statewide electoral picture. But population and registration totals alone do not show how many people will vote or which candidates they will support.
