Trade: CA-21 House Election Winner
Resolution criteria on PolyGram: This market will resolve according to the party of the candidate who wins the CA-21 congressional district seat in the U.S. House of Representatives in the 2026 midterm elections. The midterm elections will take place on November 4, 2026. A candidate's party will be determined by their ballot-listed or otherwise identifiable affiliation with that party at the time all of the 2026 House elections are conclusively called by this market's resolution sources.
PolyGram is an on-chain prediction market where you trade YES or NO outcome shares with real USDC on Polygon. For this market, buy YES if you believe the event will happen, or NO if you think it won't. Your maximum loss is your stake — winning shares pay $1.00 each at resolution. Unlike sportsbooks, there is no house edge: prices are set by supply and demand from other traders and reflect the crowd's real-time probability.
- Liquidity
- $11K
- Total Volume
- $2K
- 24h Volume
- —
- Open Interest
- $470
Market outcomes
| Democratic Party | 88% YES | 13% NO |
| A | — | |
| C | — | |
| E | — | |
| Republican Party | 12% YES | 89% NO |
| Other | — | |
| B | — | |
| D | — | |
Market context
California's 21st congressional district will elect a representative to the U.S. House in the 2026 midterm elections on 4 November. The current order book on Polymarket implies an 88% probability that a Democrat will win the seat, reflecting the district's historical lean. CA-21 encompasses parts of the Central Valley and has shifted Democratic over recent cycles, though it remains competitive enough to attract serious Republican investment in election years.
The district's recent electoral history provides the primary frame for interpreting this probability. In 2022, Democrat Jim Costa won with 52% of the vote against Republican David Valadao, whilst the 2020 presidential result saw Joe Biden secure 54% in CA-21. These margins suggest a lean-Democratic but not entirely safe seat, making the 88% implied probability a moderate reflection of Democratic structural advantage rather than an overwhelming consensus. Comparable Central Valley districts have shown volatility when national conditions shift, particularly on economic messaging.
Traders should monitor candidate announcements and primary outcomes, which typically crystallise in spring 2026. National economic conditions heading into the midterms—particularly inflation, employment, and wage growth—will likely drive significant probability shifts, as these factors historically influence swing districts. Redistricting effects should be finalised by early 2026, though CA-21's boundaries are expected to remain relatively stable. Any major shifts in turnout models or demographic changes in the district would also warrant reassessment of the current implied probability.
Wikipedia Context
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Capa HouseThe Capa House is a building in the Lindenau quarter of Leipzig, Germany at Jahnallee 61. It is named after the American war reporter and photographer Robert Capa, and is the location where Capa took The Picture of the Last Man to Die of the United States army soldier Raymond J. Bowman, who was killed there two weeks before the end of the Second World War in
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Cathouse: The Series
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Carr House, BrethertonCarr House is a 17th-century house within the Bank Hall Estate, half-way between the villages of Tarleton and Much Hoole at the extreme north-west of the village of Bretherton, Lancashire, England. The building faces south to the Bretherton road, from which it stands back some distance, and has a foreyard inclosed on the west side by farm buildings.
How this market resolves
Resolution is handled by the UMA optimistic oracle on Polygon. A proposer submits the outcome, a two-hour dispute window opens, and if no one stakes a counter-claim the payout is final. Contested outcomes escalate to UMA token-holder voting. Payouts clear in USDC to the winning side.
How to trade this market step by step
The mechanics for trading "CA-21 House Election Winner" are the same as any other PolyGram event contract. Each YES share resolves to $1 if the event happens, or $0 if it doesn't. The current price between 0¢ and 100¢ is the market's probability estimate, set live by the order book.
- Sign in on polygram.ink with your email — no full KYC under $1,500 lifetime trading volume.
- Deposit USDC on Polygon (lowest fees, ~$0.01 per transaction) or Ethereum. Funds credit after 12 confirmations.
- Pick a side. Buy YES if you believe the event will happen; buy NO if you think it won't. The current YES price reflects the market's collective probability.
- Size your position. If you stake 100 USDC at 50% YES, you'll receive shares that pay $200 if YES resolves true — a 100% gross return. If NO resolves, your shares are worth $0.
- Set risk controls (optional). Stop-loss, take-profit, and limit-order types all supported. Use the trade ticket's slippage box to cap your maximum entry price.
- Wait for resolution. When the event resolves on-chain via the UMA optimistic oracle, the winning side settles to 100¢ automatically and USDC hits your balance within seconds. Withdrawable to any wallet you control.
How active is this market?
$2K in lifetime turnover and $11K of resting liquidity puts this market in the below the median by volume for nov 4 elections contracts on PolyGram. Order-book depth is modest — expect a couple of cents of slippage on $1k+ trades.
The market has been open for 3 months — the price has had time to stabilise as new information arrived.
Higher-volume markets tend to have tighter spreads and faster price discovery — meaning the displayed YES/NO percentages are more likely to reflect the true crowd-implied probability rather than a single trader's directional view.
Key terms
- YES / NO share
- A binary outcome token that pays $1.00 if the underlying claim resolves true (YES) or false (NO), and $0 otherwise. The market price between 0¢ and 100¢ is the implied probability.
- CLOB
- Central limit order book. The matching engine that pairs YES buyers with NO buyers (effectively the same trade). Polymarket's CLOB on Polygon executes trades on-chain via the conditional-tokens framework.
- Liquidity
- USDC capital sitting in resting limit orders inside the order book. Deeper liquidity means smaller slippage on large trades and a tighter bid-ask spread.
- UMA optimistic oracle
- The on-chain dispute system that settles each Polymarket market. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution.
- Slippage
- The difference between the displayed mid-price and your fill price. Affects market orders most; limit orders avoid slippage but may take time to fill.
- Conditional token
- ERC-1155 outcome share issued by Gnosis Conditional Tokens on Polygon. The token type that resolves to $1.00 or $0.00 at settlement.
Frequently asked questions
How does this market resolve?
Resolution is handled by the UMA optimistic oracle on Polygon. A proposer submits the outcome, a 2-hour dispute window opens, and if uncontested the payout is final. Contested outcomes escalate to UMA token holders.
When does this market close?
This prediction market is scheduled to close on 3 November 2026. After the resolving event occurs, settlement typically clears within 24 hours once the UMA optimistic oracle confirms the outcome. All payouts are in USDC on the Polygon network.
How can I trade on "CA-21 House Election Winner"?
To trade on this prediction market, create a free PolyGram account at polygram.ink, deposit USDC via Polygon, and place a YES or NO order on the outcome you believe in. You can learn more on our how-it-works page. Your maximum loss is limited to your stake — there is no leverage or margin.
What happens when the market resolves?
When the outcome is determined, winning YES shares pay out $1.00 each in USDC, while losing shares pay $0. Settlement is handled by the UMA optimistic oracle on Polygon — a proposer submits the result, a two-hour dispute window opens, and if uncontested, payouts are distributed automatically. You can withdraw your winnings to any Polygon wallet.
Risk and regulatory note
Prediction-market positions can lose 100% of staked capital. Outcomes are uncertain by definition — historical accuracy of crowd-implied probabilities is high in aggregate but not for any single market. PolyGram does not provide investment advice. Trade only with capital you can afford to lose.
Regulatory status varies by jurisdiction. Germany, the United States, and most EU countries treat Polymarket-style event contracts under one of three frameworks: financial derivative, gambling product, or unregulated novel asset. Consult local counsel before trading.
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