Indianapolis 500 2025

The Indy 500 doesn't create traffic, it moves it.

The Indianapolis 500, the world's largest single-day sporting event with ~275,000 attendees, created a dual-layer traffic effect on race day (May 25, 2025). The race suppressed normal traffic across Indiana and Indianapolis while creating an extreme surge at the venue itself.

Indiana statewide rides dropped −16.7% on race day and Indianapolis fell −17.3% (Z = −10.98). Meanwhile, Speedway, IN, the 2.5-square-mile municipality hosting IMS, saw a +108.7% surge. The event reshapes the network entirely.

275,000 people in one 2.5-square-mile city.

The Indianapolis 500, "The Greatest Spectacle in Racing," has been held at the Indianapolis Motor Speedway in Speedway, Indiana every May since 1911. The 2025 edition ran on Sunday, May 25, also Memorial Day weekend, with an estimated 250,000-300,000 spectators, making it the largest attended single-day sporting event in the world. The road network around it does not behave normally.

Known race-day road impacts: major closures around IMS (16th Street), restricted Georgetown Road, high congestion on I-465 approaches all day, and ~30,000 dedicated IMS parking spaces used.

Methodology

Data source. Primary table: nexar-data-warehouse.Intermediate.IT_TRX_RIDE_LOCATIONS_CLASSIFIER, partitioned by ride_start_date. Vehicle classification leverages the vehicle_classification_predictions model (run_month: April 2026). All queries filtered to country = 'United States of America'.

Baseline construction. Three comparison Sundays were selected: May 4, May 11, and May 18, 2025. These satisfy: same day-of-week (Sunday), same month (May), same year (2025), and no known major events. The average of these three days forms the baseline for all comparisons. Geographic granularity runs National, Indiana state, Indianapolis, and Speedway / IMS. Metrics: total ride count, total miles, total hours, hours/ride & miles/ride, active rides per hour, and % change and Z-score vs baseline.

National traffic overview.

At the national level, Memorial Day Sunday 2025 showed a modest but consistent reduction in Nexar fleet activity compared to prior Sundays in May. The national signal anchors the Indy-specific findings on the pages that follow.

Indiana shows the strongest suppression.

Indiana shows the strongest suppression signal in the study. Race day rides fell to 1,963, well below the baseline average of 2,356 (−16.7%). The result is statistically highly significant (Z = −2.68, p < 0.01).

The clearest race-day suppression.

Indianapolis proper, the city surrounding the IMS venue, shows the clearest race-day suppression. The drop from a baseline of 372 average rides to just 308 on race day (−17.3%) is statistically extraordinary: Z = −10.98, corresponding to p < 0.0001.

While the city suppresses, the venue surges.

Speedway, the 2.5 sq-mile municipality that hosts the Indianapolis Motor Speedway, tells a completely different story. On race day, Nexar recorded 32 rides starting in Speedway, compared to a baseline average of just 15.3 rides per Sunday, a +108.7% surge.

A clear geographic pattern.

Top Indiana cities reveal a clear geographic pattern: cities close to IMS or connected by major race-day travel corridors see divergent outcomes. Most decreased; a few in the northwest (Chicago corridor) or venue-adjacent areas increased.

IMS-adjacent and Chicago-corridor cities (Speedway, Schererville, Hobart, Jeffersonville) show above-baseline patterns, likely Memorial Day weekend travel to and from Chicago and race-adjacent activity. Indy suburbs (Fishers, Carmel, Noblesville) show modest −5% to −14% declines. Secondary cities (Bloomington, Fort Wayne, Evansville, Avon) show larger −22% to −39% declines, consistent with residents leaving for Indianapolis or out-of-state destinations.

Trucks took the biggest hit.

Nexar fleet vehicles in Indiana are classified using machine learning predictions (run_month: April 2026). Taxi/Rideshare dominates the Indiana fleet, followed by Trucks and Consumers.

The race window is a dead zone.

Hourly active-ride counts in Indianapolis reveal a distinct race-day signature. Each ride is counted in every hour it was active (not just the start hour), in local Eastern Time. The deepest suppression hits during the 1-4 PM ET race window.

Statistically extraordinary.

Z-score analysis across the three geographic tiers. The Indianapolis Z of −10.98 is the analytical centrepiece, orders of magnitude beyond conventional significance thresholds.

The data relocated the venue.

External benchmarks are drawn from publicly known statistics and FHWA special-events guidance. Four of five Nexar findings are directly validated; the fifth is explainable by the unique structure of the Indy 500.

Insights & recommendations.

Three key insights translated into stakeholder recommendations, useful for fleet operators, rideshare networks, insurance/risk teams, and city planners.

1. Venue absorption model

   Large motorsport events create traffic voids, not surges, in the host city. Unlike concerts or ballgames where attendees take rideshare, Indy 500 attendees drive personal vehicles and use venue parking. The net effect is city-wide traffic suppression during race hours. Fleet operators should expect significantly reduced demand in Indianapolis during 12-4 PM ET on race day.

2. Race window = dead zone

   12:45-3:45 PM is unusable for Indianapolis fleet. Active rides drop up to −48% below baseline during the race. For logistics operators, scheduling Indiana deliveries before 11 AM or after 5 PM on race day maximises efficiency and avoids road-closure disruptions.

3. Post-race opportunity window

   5-7 PM ET, rapid recovery, capture-able demand. By 6 PM ET, Indianapolis ride activity is back to baseline (+5%). Fleet operators and rideshare drivers positioned near IMS exit routes (I-465, Georgetown Road) after ~3:45 PM can capture elevated demand as 275K+ spectators depart.

Limitations & caveats.

1. Geographic attribution

   Trips are attributed to the starting city. Cross-state race visitors (from Ohio, Illinois, Michigan) who started their trip outside Indiana are not captured in Indiana counts.

2. Speedway sample size

   Only 15-32 rides per day in Speedway, IN, directionally valid but not sufficient for high-precision estimates. The +108.7% finding should be read as a robust indicator, not a calibrated number.

3. Memorial Day confound

   May 25, 2025 is both race day and Memorial Day Sunday. The study isolates the net ~−11.8 pp IMS effect vs national baseline, but the two effects cannot be fully disentangled from a single data point.

4. Fleet representation

   Nexar captures commercial and consumer dashcam-equipped vehicles, not all vehicles on Indiana roads. Bias may exist toward commercial fleets, especially in less-populated cities.

5. External sources

   Web search API was unavailable during this study; external benchmarks are based on publicly known FHWA guidance and general knowledge, not primary research retrieval. Section 12 is a triangulation, not a literature review.

6. Race-day-only scope

   This study focuses on race day (May 25) only. The full 12-day venue period (May 14-25, practice, qualifying, race) is a recommended follow-up study to capture build-up effects.

Appendix · raw data tables.

Daily series and vehicle classification breakdowns, for reproducibility.

National Daily Totals

Indiana State Daily Totals

Indiana Vehicle Type · Race Day Breakdown

Data sources · Primary table nexar-data-warehouse.Intermediate.IT_TRX_RIDE_LOCATIONS_CLASSIFIER · Partition filter ride_start_date IN ('2025-05-04', '2025-05-11', '2025-05-18', '2025-05-25') · Vehicle classification nexar-data-warehouse.MLP.vehicle_classification_predictions (run_month = 2026-04-01) · Geographic filter country = 'United States of America', state = 'Indiana' · Timezone UTC to America/Indiana/Indianapolis (ET) · Distance meters ÷ 1609.34 to miles · Duration seconds ÷ 3600 to hours.