US Political Betting Statistics 2016, 2020, 2024

Political betting markets have emerged as a significant alternative forecasting tool for elections in recent years, operating on the principle that people putting real money at stake creates powerful incentives for accuracy. These markets aggregate the collective wisdom and information of thousands of participants worldwide, potentially capturing insights that traditional polling might miss.

This comprehensive analysis examines political betting statistics across three pivotal US elections: 2016, 2020, and 2024. 

1. Market Size and Evolution (2016-2024)

Total Betting Volume Growth

The growth in political betting volume from 2016 to 2024 has been nothing short of extraordinary, reflecting both increased public interest in elections and the expanding accessibility of betting platforms.

2016 Election Volume

The 2016 US presidential election between Donald Trump and Hillary Clinton was, at the time, the most wagered-upon political event in history. According to data from betting exchanges and media reports:

• Approximately $250-300 million was wagered globally
• Betfair Exchange alone matched approximately $277 million in bets
• This volume represented unprecedented interest in political betting

As reported by CNBC and Reuters at the time, the contentious nature of the race drove record participation from bettors, particularly in the UK and other international markets where political betting was legal and well-established.

2020 Election Volume

The 2020 election between Donald Trump and Joe Biden shattered all previous records, driven by high political engagement and the expanding accessibility of betting platforms:

• Record-setting approximately $2.2 billion wagered globally
• Betfair Exchange alone handled nearly $2 billion in matched bets
• Individual wagers reached unprecedented levels, including a £1 million ($1.29 million) single bet on Biden

According to Newsweek, the 2020 election drew more betting interest than previous Super Bowls, highlighting how political wagering had moved from niche activity to mainstream popularity. Mike Norman of Betfair described it as “the race that broke all records” in a subsequent analysis.

2024 Election Volume

The 2024 election between Donald Trump and Kamala Harris saw yet another dramatic leap in betting volume:

• Polymarket alone recorded $3.7 billion in total trading volume for the presidential election
• Polymarket’s “Presidential Election Winner 2024” market crossed $2 billion in October 2024
• Other platforms added significant volume: Kalshi ($235 million) and PredictIt ($44 million)

This phenomenal growth reflects both the increasing global interest in US politics and the evolution of crypto-based prediction platforms that enabled international participation despite regulatory restrictions.

Platform Market Share and Growth

The landscape of political betting platforms has evolved considerably across these three elections, with established players maintaining dominance while new entrants introduced technological innovations.

Betfair Exchange

• Maintained position as the dominant player, handling approximately 80-90% of global political betting in 2016 and 2020
• Benefited from UK regulatory approval and established customer base
• Provided high liquidity with sophisticated market-making mechanisms

PredictIt

• Grew from approximately 22,000 traders in 2016 to over 80,000 traders by 2018
• During peak months of the 2016 election cycle, attracted up to 17,000 new traders per month
• Operated under CFTC regulatory constraints, including $850 maximum investment limits per contract

Polymarket

• Emerged as a major player by 2024, utilizing blockchain technology
• Reached nearly 100,000 active monthly users by late 2024
• Crypto-based structure enabled global participation despite US regulatory restrictions

Kalshi

• New entrant that gained legal approval to offer election betting in the US for the first time in 2024
• Represented a significant regulatory breakthrough in the American market

Geographic Distribution of Betting Activity

Political betting on US elections has been predominantly an international activity, with significant concentration in specific regions due to regulatory considerations.

UK Dominance

The United Kingdom has consistently been the epicenter of political betting activity:

• UK-based Betfair handled the majority of wagering in both 2016 and 2020
• British bettors constituted the largest geographic segment of participants
• UK regulatory framework provided legal clarity unavailable in the US

US Participation Constraints

American bettors have faced significant restrictions:

• Most US citizens legally barred from participating in political betting markets
• US bettors were explicitly banned from Polymarket in 2024
• PredictIt operated under strict CFTC limitations, capping individual exposure
• Kalshi’s 2024 court victory briefly opened legal US-based election betting before appeals

International Expansion

The 2024 election saw truly global participation:

• Crypto-based platforms like Polymarket enabled worldwide access
• Participation from Europe, Asia, and other regions increased significantly
• Technological innovations reduced entry barriers for international bettors

2. The 2016 Election – The Polling Miss and Betting Markets

Hillary Clinton’s Dominant Position

As Election Day approached in 2016, betting markets strongly favored Hillary Clinton over Donald Trump:

• Clinton was given approximately an 80-85% chance of winning on election day across major betting sites
• Betfair Exchange showed Clinton at 1.29 odds (implying ~77% probability of victory)
• UK betting firms consistently messaged high confidence in a Clinton victory

These odds reflected conventional wisdom at the time, which was heavily influenced by polling data showing Clinton with consistent leads in national surveys and many battleground states.

The Trump Upset

The actual results delivered one of the most dramatic market reversals in political betting history:

• Trump’s odds shifted dramatically on election night as results from key states came in
• Betfair’s “Classic Exchange Stories” documented what traders called “the most dramatic market movement in history”
• Within hours, Trump moved from a longshot to heavy favorite as returns from Pennsylvania, Michigan and Wisconsin defied expectations

This reversal stands as one of the most significant prediction market failures in recent history, though it’s worth noting that traditional polling and forecasting models performed even worse in many cases. FiveThirtyEight gave Trump a 28.6% chance on Election Day—higher than most models but still significantly underestimating his actual prospects.

Market Accuracy Assessment

The 2016 failure represents a significant data point in assessing prediction market reliability:

• It was the only presidential election since 1980 where betting markets failed to predict the winner
• However, PredictIt data shows significant contrarian Trump betting, suggesting some market participants correctly assessed his chances
• The failure highlighted how prediction markets can be vulnerable to the same information cascades that affect polling and conventional wisdom

3. The 2020 Election – Volatility and the “Red Mirage”

Pre-Election Market Assessment

Betting markets approached the 2020 election with more caution, learning from the 2016 experience:

• Biden maintained a consistent but narrower advantage in betting odds than polling suggested
• Record-setting individual wagers included a £1 million ($1.29 million) bet on Biden placed on Betfair
• COVID-19 impacts on campaigning and voting methods created additional uncertainty

The “Red Mirage” Effect

The 2020 election night produced extraordinary volatility in betting markets:

• Trump’s odds dramatically improved on election night, with his probability rising to nearly 80% on Smarkets as initial returns favored Republicans
• This “red mirage” effect occurred as expected, reflecting the tendency of in-person votes (counted first) to favor Republicans
• As mail-in ballots were counted in subsequent days, Trump’s chances fell sharply to 21% on Smarkets
• Markets ultimately stabilized with Biden as the heavy favorite as mail-in votes were tallied

This pattern revealed how betting markets could be susceptible to temporary information asymmetries, but ultimately adjusted to incorporate new data.

Predictive Accuracy

Despite the election night volatility, betting markets ultimately performed with remarkable accuracy in 2020:

• Correctly predicted Joe Biden’s victory
• Accurately forecasted outcomes in 49 out of 50 states
• Projected Biden at approximately 310 electoral votes, very close to the actual 306
• Successfully anticipated tighter-than-polled margins in Florida and Pennsylvania

This performance represented a significant recovery from the 2016 miss and suggested that markets had incorporated lessons from that experience.

4. The 2024 Election – New Dynamics and Record Engagement

Biden Withdrawal Impact

The 2024 election cycle featured unprecedented market volatility following President Biden’s withdrawal:

• Markets reacted swiftly when Biden withdrew and Kamala Harris became the nominee
• Harris’s odds of securing the nomination quickly shortened to 8/13 (1.6), indicating a greater than 60% chance
• Polymarket recorded significant volume spikes, with single-day trading exceeding $28 million following Biden’s exit

This event demonstrated the markets’ ability to rapidly process major political developments and recalibrate expectations.

Final Market Assessments

As Election Day 2024 approached, a notable divergence emerged between betting markets and traditional polling:

• Polymarket showed Trump with a 60-67% probability of winning
• Traditional polling averages indicated a much closer race, often within the margin of error
• This divergence became a significant media narrative in the campaign’s final weeks

The confidence of betting markets in Trump’s prospects contrasted sharply with the conventional wisdom of a toss-up race, raising questions about which forecasting method would prove more accurate.

Predictive Accuracy

The 2024 election results ultimately validated betting market predictions:

• Markets correctly anticipated Donald Trump’s victory over Kamala Harris
• The substantial advantage given to Trump (60-67%) was directionally accurate
• This success followed the accurate prediction of the 2020 outcome, suggesting improved reliability

Accusations of Market Manipulation

The 2024 cycle also featured unprecedented scrutiny of market integrity:

• Research identified patterns suggesting potential “wash trading” to inflate volumes on Polymarket
• Some analysis suggested a handful of pro-Trump bettors had placed over $25 million on the platform
• Polymarket launched an investigation into potential market manipulation for a pro-Trump influence campaign
• Critics questioned whether these patterns affected price accuracy or merely volume statistics

These concerns highlighted the growing significance of betting markets in shaping election narratives and the increased scrutiny they face as their influence expands.

5. Comparative Analysis – Markets vs. Polls & Models

Predictive Accuracy Across Elections

Analyzing the three elections collectively reveals interesting patterns in market performance:

• Betting markets correctly predicted the winner in 2020 and 2024, but missed in 2016
• Markets generally demonstrated better calibration than polls, especially in identifying close races
• Real-time responsiveness to events and new information allowed markets to adjust faster than polling aggregators
• However, the “favorite-longshot bias” occasionally appeared, particularly in overestimating longshot candidates in primaries

Economist Koleman Strumpf, who has studied political betting for over two decades, notes that betting markets have historically outperformed polls in election forecasting accuracy, particularly in volatile or close elections.

Case Studies of Market Responsiveness

Several specific cases highlight the predictive potential of political betting markets:

2020 Democratic Primaries

• Markets rapidly adjusted after Biden’s South Carolina win
• Odds shifted to favor Biden for the nomination before polling consensus identified his momentum
• This demonstrated the markets’ ability to quickly process new information

Georgia Senate Runoffs (2021)

• Betting markets accurately transitioned these races from Republican-favored to toss-ups
• This shift preceded polling data showing the Democratic advantage that ultimately materialized
• Illustrated how markets can identify emerging trends ahead of traditional metrics

Notable Upsets and Market Failures

Markets have not been infallible, with several notable misses:

2016 U.S. Presidential Election

• Hillary Clinton heavily favored (~85%) until Trump’s upset victory
• Represented the most significant market failure in recent US electoral history

Brexit Referendum (2016)

• Incorrectly favored “Remain” with approximately 90% probability
• Demonstrated markets’ susceptibility to the same information bubbles that affect polling

2022 U.S. Senate Elections

• Markets misjudged the likelihood of Democratic Senate control
• Reflected overconfidence in historical trends about midterm elections

These failures suggest markets still have blind spots, particularly when conventional wisdom is strong and contrary indicators are dismissed.

6. The Influence of Betting Markets

Media Coverage of Betting Odds

Political betting odds have gained increasing prominence in election coverage:

• Major news outlets now routinely report betting odds alongside polling averages
• In 2024, Polymarket odds became a frequent reference point in coverage of the presidential race
• The divergence between betting markets and polling averages became a major narrative
• Media outlets like Forbes, Fortune, and NPR devoted significant coverage to explaining the gap

This increased visibility has raised questions about whether betting odds influence public perception of races independently of polling data.

Impact on Public Perception

Evidence suggests betting markets increasingly shape how elections are perceived:

• Odds showing a candidate with a substantial lead can create momentum narratives
• The accessibility of probability percentages (e.g., “Trump has a 67% chance of winning”) provides clearer framing than complex polling averages
• Market movements generate news coverage that amplifies their impact

Some campaigns and political analysts have expressed concern that betting odds could influence voter turnout by affecting perceptions of how close a race truly is.

Campaign Response to Betting Markets

Campaigns have begun to monitor betting markets as a barometer of public perception:

• Several 2024 campaign staffers acknowledged tracking betting odds as a supplementary metric
• Campaigns increasingly factor market responses into their assessment of debate performances and policy announcements
• However, no definitive evidence exists that campaigns have deliberately tried to manipulate these markets

7. Regulatory Context & Impact

Legal Environment in U.S.

The regulatory landscape for political betting in the United States remains complex:

• Political betting has been mostly illegal or heavily restricted in the U.S., with limited exceptions
• The CFTC revoked PredictIt’s regulatory exemption in 2022, creating uncertainty in the market
• In 2024, a U.S. court briefly allowed election betting on platforms like Kalshi before an appeals court reviewed the decision
• This legal flux has created barriers to full market development

Impact of Regulations

Evidence suggests regulations significantly impact market efficiency:

• Legal restrictions limit market depth and liquidity
• Lower participation from informed U.S. bettors potentially decreases predictive accuracy
• Regulatory uncertainty discourages institutional involvement that could improve efficiency

Economist Koleman Strumpf has argued that if political betting were fully legalized in the US, market volumes could potentially double from current levels, with corresponding improvements in accuracy.

Future Regulatory Outlook

The regulatory environment continues to evolve:

• Kalshi’s partial victory in 2024 suggests courts may be increasingly receptive to election betting
• CFTC positions remain skeptical of political event contracts
• The growing international popularity of political betting creates pressure for regulatory clarity

This evolving landscape will significantly influence the future development of political betting markets.

8. The Future of Political Betting

Technology and Market Evolution

Several key technological trends are shaping the future of political betting:

• Cryptocurrency-based platforms have reduced international barriers to participation
• Smart contracts enable more complex betting structures and automatic settlement
• Real-time data integration allows for more nuanced market reactions to events
• Mobile accessibility has expanded the participant base beyond traditional betting demographics

These innovations suggest political betting will continue to grow in sophistication and reach.

Potential Volume Growth

If current trends continue and regulatory barriers diminish:

• US election betting volume could potentially reach $5-10 billion by the 2028 election cycle
• Increased participation from US-based bettors would significantly deepen market liquidity
• Institutional involvement would likely grow if regulatory clarity improves
• The predictive power of these markets could substantially increase with greater participation

Conclusion

Political betting markets have evolved from a niche activity to a significant forecasting tool across the 2016, 2020, and 2024 election cycles. The explosive growth in betting volumes—from approximately $300 million in 2016 to over $3.7 billion in 2024—reflects both increased public interest and technological innovations that have expanded access globally.

Their predictive record is mixed but improving. After the significant miss in 2016, betting markets correctly anticipated the outcomes of both the 2020 and 2024 presidential elections, often with greater accuracy than traditional polling. The real-time responsiveness of these markets to new information, combined with the financial incentives for accuracy, suggests they provide valuable complementary insights to conventional forecasting methods.

As this field continues to evolve, this analysis serves as a foundation for understanding past trends and anticipating future developments in political betting across subsequent election cycles.

References

Volume and Market Data

• Betfair Exchange. (2016, 2020, 2024). Political betting data and press releases.
• Polymarket. (2024). Trading volume data for 2024 presidential election.
• PredictIt. (2016, 2018, 2020, 2024). Market archives and trader statistics.
• Kalshi. (2024). Trading data for 2024 election markets.

News and Analysis Sources

• CNBC. (2016). “Betting sites see record wagering on US presidential election.” https://www.cnbc.com/2016/11/07/betting-sites-see-record-wagering-on-us-presidential-election.html
• Reuters. (2016). “Betting sites see record wagering on U.S. presidential election.” https://www.reuters.com/article/us-usa-election-gambling/betting-sites-see-record-wagering-on-u-s-presidential-election-idUSKBN1320HW/
• Forbes. (2024). “Polymarket’s $3.2 Billion Election Bet Shows Web3 Potential.” https://www.forbes.com/sites/digital-assets/2024/11/05/polymarkets-32-billion-election-bet-shows-web3-potential/
• Fortune. (2024). “Polymarket Trump election crypto wash trading researchers.” https://fortune.com/crypto/2024/10/30/polymarket-trump-election-crypto-wash-trading-researchers/
• Newsweek. (2020). “2020 Election Draws Billions in Bets, More Than Previous Super Bowls.” https://www.newsweek.com/2020-election-draws-billions-bets-more-previous-super-bowls-1544203
• Sky News. (2020). “US election 2020: Betting markets shift back towards Joe Biden.” https://news.sky.com/story/us-election-2020-betting-markets-shift-back-towards-joe-biden-12123634
• Decrypt. (2024). “US Presidential Election Tops $2 Billion in Betting Volume on Polymarket.” https://decrypt.co/286923/us-presidential-election-2-billion-volume-polymarket
• New York Times. (2024). “Prediction markets Trump-Harris.” https://www.nytimes.com/2024/10/15/business/dealbook/prediction-markets-trump-harris.html
• NPR. (2024). “Election prediction market favors Trump with 2/3 odds despite toss-up polls.” https://www.npr.org/2024/10/29/nx-s1-5132616/election-day-betting-trump-harris

Academic and Expert Analysis

• Strumpf, K. (2024). “Election predictions: Economist shares insights from political betting markets.” Wake Forest News. https://news.wfu.edu/2024/10/24/election-predictions-economist-share-insights-from-political-betting-markets/
• University of Cincinnati. (2024). “Election results show potential of prediction markets.” https://www.uc.edu/news/articles/2024/12/election-results-show-potential-of-prediction-markets.html
• Political Prediction Markets. (2018). “Volume and Liquidity on PredictIt.” https://politicalpredictionmarkets.com/volume-and-liquidity-on-predictit/
• SBCA. (2024). “CFTC Losses Legal Battle Against Kalshi Over Political Bets.” https://sbcamericas.com/2024/09/10/kalshi-judge-cftc-political-contracts/