Polymarket
KalshiTX-21 Is Priced as a Republican Hold Because the Line Is Doing the Work an Incumbent Used To
TX-21 House race odds are a question about a map, not a candidate. The seat as drawn for 2026 runs through Bandera, Blanco, Comal, Gillespie, Kendall, Kerr and Real counties, a 17% slice of Bexar County and almost half of Hays County, and the Republican presidential ticket carried it by more than twenty points in 2024 within the new lines. Texas voters decide the seat on November 3, 2026 with no incumbent on the ballot, and the market treats the district line as the whole race: the Republican contract has been the heavy favourite on both venues since primary day, and the live board above shows where it sits. The price rests on the line and on the money, not on either nominee, and the sections below say what would make that wrong.
What the TX-21 price is saying
The district itself is the first thing the price is saying. Under PlanC2333, the congressional map the 89th Legislature enacted in its second called session of 2025 and the plan in effect for the 2026 elections, TX-21 takes Bandera, Blanco, Comal, Gillespie, Kendall, Kerr and Real counties whole, 17% of Bexar County and 45% of Hays County, for a population of 766,987. The Texas Legislative Council's analysis of the November 5, 2024 general election within those lines gives the Republican presidential ticket 60.2% to 38.5% and the Republican Senate ticket 57.7% to 40.1%, on 601,401 registered voters and a 69.4% turnout. A seat with that record is priced as a hold before either nominee has spent a dollar, because a twenty-two point presidential gap is larger than any swing a House campaign has to explain.
The redraw changed this seat less than it changed the map. Under the previous plan, PlanC2193, the district held 84% of Comal County, 43% of Hays County and a 2% sliver of Travis County; the 2025 plan gave it all of Comal, a slightly larger share of Hays and none of Travis, and redrew the Bexar County portion so that the Anglo share of that piece fell from 45.2% to 40.1% of its population. Across the whole district the Anglo share moved from 58.9% to 54.3% and the Hispanic share from 30.7% to 34.6%, on the 2020 Census counts the council publishes with each plan. Run the November 5, 2024 vote through both maps and the presidential margin moves by about a point, from 61.1% to 37.6% under the old line to 60.2% to 38.5% under the new one, which means the redraw traded some demography for almost no partisanship. The line moved; the seat did not.
The second thing the price is saying is that an open seat in a district like this is still a party question. The sitting member for TX-21 is Chip Roy of Austin, a Republican sworn in on January 3, 2025 according to the Clerk of the House's member list for the 119th Congress, and his name is not on the Secretary of State's candidate list for the seat, in either party's March 3, 2026 primary or the November general election. Twelve Republicans filed for the primary between November 8 and December 8, 2025. The certified general-election list carries two names: Mark Teixeira for the Republican Party, who filed on November 8, 2025 and listed his occupation as retired, and Kristin Hook for the Democratic Party, a scientist from San Antonio who filed on December 8, 2025. Hook was the Democratic candidate against Roy in the November 5, 2024 general election and took 153,765 votes, 36.06%, to his 263,744, 61.85%, with a Libertarian at 2.09%, under the old lines. The market has the same two parties and a familiar Democratic name; what it lacks is an incumbent, and the price says that absence is worth little here.
The third thing is money, and it is lopsided. Federal Election Commission totals through June 30, 2026 show Teixeira's campaign with $3.92M in receipts, $3.54M in disbursements and $382.2K in cash on hand; Hook's shows $243.8K raised, $144.1K spent and $104.1K on hand. Sixteen to one in receipts is the kind of gap that decides whether a challenger can be heard at all, and the market has priced it: a contract that would need a Democratic surge to pay has no evidence of one in the filings.
The price found that read in stages, and the stages are on the record. Polymarket's Republican contract opened on January 30, 2026 at 52.5%, printed as low as 41.5% on February 4, 2026 while the twelve-way primary was unresolved, and stood at 78.5% on March 3, 2026, primary day. It was 85.5% on April 1, 80% on May 1, 77.5% on June 1, 86.5% on July 1, 92% on September 1 and 93.5% on September 23, 2026. A market that opened near even and reached the high seventies on primary day was pricing the primary, not the district; the climb since July tracked the money and the calendar, and nothing in that path is a reaction to the general-election campaign itself.
Two venues price the seat and they agree. On September 23, 2026 Kalshi's Republican contract was 95% and Polymarket's 94%; the Democratic contracts were 7% and 6%. Matched volume across both books was $74.1K, with $64.3K of it on Polymarket ($34.2K on the Republican outcome, $30.2K on the Democratic one) and $9.8K on Kalshi ($4.0K and $5.8K), which is thin for a House seat and consistent with a contract nobody expects to move. A one-point gap between two books is one read in two places, not two reads.
The case against the TX-21 read
The case against the read starts from the absence of an incumbent. The 61.85% the seat returned on November 5, 2024 was earned by a name that is not on the ballot, and the Republican candidate who replaced it, whose first federal filing is dated August 28, 2025, spent $3.54M of $3.92M raised to get through a twelve-candidate primary, leaving $382.2K on hand at June 30, 2026, less than four times Hook's $104.1K. The receipts gap is sixteen to one; the cash gap is under four to one. If the general election is fought on what is left rather than on what was raised, the money argument is weaker than the headline number, and a reader who holds the other view says an open seat is priced like a held one because nobody has yet tested the difference.
The demography moved more than the vote did. The redraw pushed the district's Hispanic share from 30.7% to 34.6% of population and its Anglo share below 55%, and the two pieces that are not the rural counties, the 45% of Hays County and the 17% of Bexar County, are where that change sits: the Hays portion is 57.0% Anglo and the Bexar portion 40.1%. The November 5, 2024 presidential vote inside the new lines shifted only a point because the added precincts voted much as the departed ones did in a presidential year; a midterm electorate is a different one, and the council's own table has this district's turnout at 55.6% in the 2022 general election against 69.4% in 2024. The record does not say which side a smaller electorate helps here, and a price in the mid-nineties assumes the answer.
The market has already disagreed with itself once. Polymarket's Republican contract printed 41.5% on February 4, 2026, and it was still 77.5% on June 1, 2026, three months after the primary, which means traders did not fully accept the nominee until July. A book that took four months to settle on a district with a twenty-two point presidential margin was pricing something other than the line, and whatever that was has been outlasted rather than answered.
What changes the TX-21 read
The read is wrong if the campaign, not the map, starts moving the price. The number to watch is the Democratic contract, and the dates are the state's.
• The Democratic contract on both books: it has not closed above 13% on Polymarket since August 1, 2026; a hold above 20% on both venues after early voting opens on October 19, 2026 would say the market is pricing a person, and this read would be dead.
• The next federal fundraising reports: the totals above run through June 30, 2026; the reports that follow are the first evidence of whether Teixeira's cash was rebuilt after the primary or whether Hook's small book grew.
• Early voting, October 19 to October 30, 2026: county early-vote counts in Comal, Hays and Bexar are the first read on whether the midterm electorate looks like 2024's; a turnout shape that leans toward the Bexar and Hays portions is the one this price does not anticipate.
• A fixed ballot: August 21, 2026 was the last day to withdraw from or be declared ineligible for the general election, so the two names are set and only a vacancy changes the line-up; voter registration closes on October 5, 2026.
When the TX-21 market resolves
Texas holds the general election on Tuesday, November 3, 2026, with early voting from October 19 through October 30 and voter registration closing on October 5, 2026. Polymarket's contracts resolve on the party of the candidate who wins the seat, by ballot-listed affiliation at the time all 2026 House elections are conclusively called by a consensus of credible reporting, with the Federal Election Commission's official results as the tiebreaker if reporting is ambiguous; the event's listed end is November 4, 2026 at 04:59 UTC. Kalshi's contracts pay Yes if the House member sworn in for TX-21 for the term beginning in 2027 belongs to the named party, allow accelerated determination once a consensus of media organizations projects the winner, expect settlement on January 4, 2027, carry a listed expiration of November 3, 2027 and close following the swearing-in. Members elected under the previous plan continue to represent the old districts until the next Congress convenes in January 2027. Each venue also lists a contract on another party winning the seat; Polymarket's carried no volume on September 23, 2026, and the Secretary of State's list carries no third name for TX-21.
Related TX-21 markets
The two other House seats this site follows on the same map are the Texas 24th District market, a held Republican seat in Tarrant and Dallas counties where the incumbent is on the ballot, and the Texas 28th District market, the South Texas seat the redraw changed most. Both resolve on the same November 3, 2026 vote and on the same party rule. The Texas politics hub carries the full set of state boards, the elections page lists every race with a contract, and the markets catalogue has the rest of the Texas inventory.
