ThatCarHitMe.com
An Injuria.ai Company
YEAR-OVER-YEAR CRASH REPORT · CHICAGO, IL · MAY 2021
Purpose: Machine-readable JSON endpoint for AI agents, LLMs, researchers, and programmatic consumers. Returns all underlying crash data and AI-generated commentary without HTML.
Authentication: None required. Public endpoint.
GET: https://thatcarhitme.com/api/crash-data/reports/data/illinois/chicago/may-2021-report
Monthly Traffic Safety Analysis
9,651 CRASHES IN
CHICAGO, IL
MAY 2021
In May 2021, Chicago experienced a significant increase in traffic incidents compared to May 2020. Total crashes rose from 6,548 to 9,651, marking a 47.4% increase. Fatalities also increased by 28.6%, from 14 in May 2020 to 18 in May 2021, representing a notable year-over-year shift in crash outcomes.
9,651
▲ 47.4%was 6,548
Total Crash Events
18
▲ 28.6%was 14
Persons Killed
2,084
▲ 43.1%was 1,456
Persons Injured
3,359
▲ 38.3%was 2,428
Hit-and-Run Crashes
Note: "Persons Killed" (18) counts individual fatalities across all crash events. "Fatal" in the severity table below (18) counts crash events where at least one fatality occurred. A single crash can result in multiple fatalities. 15 crashes with unreported severity are not shown in the severity breakdown.
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-05-01 to 2021-05-31 · Aggregate counts from crash, person, and vehicle records
Trend Summary
Overall, crash data indicates a rising trend year-over-year. Total crashes increased by 47.4%, from 6,548 in May 2020 to 9,651 in May 2021. Similarly, total injuries rose by 43.1%, from 1,456 to 2,084, reflecting a substantial increase in traffic incidents and their human impact.
3,359
Hit-and-Run Crashes — May 2021
▲ 38.3% vs prior (2,428)
Hit-and-run crashes increased by 38.3%, from 2,428 in May 2020 to 3,359 in May 2021. However, the hit-and-run rate relative to total crashes decreased from 37.1% to 34.8% year-over-year. This indicates that while the absolute number of hit-and-run incidents rose, their proportion of all crashes slightly declined.
Vulnerable Road User Casualties
3
Pedestrians Killed
1
Cyclists Killed
14
Motorists Killed
0
Other Killed
165
Pedestrians Injured
100
Cyclists Injured
1,817
Motorists Injured
2
Other Injured
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-05-01 to 2021-05-31 · Mode classified from person records (driver/passenger → motorist; pedestrian; bicyclist → cyclist; in-line skater / unspecified → other)
When Crashes Happen
The peak day for crashes shifted from Friday in May 2020 (1,190 crashes) to Saturday in May 2021 (1,650 crashes). The peak hour also moved from 3 PM in May 2020 (538 crashes) to 4 PM in May 2021 (768 crashes). Crashes increased across all days of the week, with Monday seeing the largest percentage increase of 103.9% (from 717 to 1,462 crashes).
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-05-01 to 2021-05-31 · Crash date field aggregated by weekday
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-05-01 to 2021-05-31 · Crash time field aggregated by hour (0-23)
Crash Severity Breakdown
While the total number of fatalities increased from 14 to 18 (a 28.6% rise), the fatal crash rate slightly increased from 0.17% to 0.19%. Serious injuries increased in count from 150 to 207, but their proportion of total crashes slightly decreased from 2.3% to 2.1%. Overall, total injuries rose by 43.1% year-over-year, from 1,456 to 2,084.
Outcome by Severity (Crash Events)
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-05-01 to 2021-05-31 · KABCO injury classification scale
Severity Distribution
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-05-01 to 2021-05-31 · Most severe injury per crash record
Top Contributing Factors
The top contributing factor, 'FAILING TO YIELD RIGHT-OF-WAY,' increased by 340 crashes (51.4%) from 661 to 1,001, maintaining its top rank. 'FOLLOWING TOO CLOSELY' also saw a 43.1% increase, rising by 240 crashes from 557 to 797. 'IMPROPER OVERTAKING/PASSING' experienced a 73.9% increase, growing by 201 crashes from 272 to 473, moving from fourth to third rank.
Officer-Reported Primary Contributing Cause
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-05-01 to 2021-05-31 · Officer-reported primary contributory cause per crash
Road & Environmental Conditions
Crashes occurring under clear weather conditions increased in proportion from 82.0% to 83.2% of all crashes. Conversely, crashes in rainy conditions saw their proportion decrease from 11.5% to 8.5%. Similarly, crashes on dry road surfaces increased proportionally from 79.1% to 81.8%, while those on wet surfaces decreased from 14.5% to 10.7%.
Weather
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-05-01 to 2021-05-31 · Weather condition at time of crash
Lighting
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-05-01 to 2021-05-31 · Lighting condition field
Road Surface
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-05-01 to 2021-05-31 · Road surface condition field
Vehicles & Demographics
The total number of vehicles involved in crashes increased by 44.5%, from 13,738 to 19,848. Chevrolet remained the most common vehicle make, with its involvement in crashes increasing by 33.2% (from 1,828 to 2,435). Toyota's involvement saw a 60.4% increase (from 1,193 to 1,914), moving it from third to second place in rankings.
Top Vehicle Makes (19,848 vehicles)
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-05-01 to 2021-05-31 · Vehicle unit records
6,570 persons with unknown or unrecorded age excluded from age chart. Age=0 in Chicago records is a sentinel for unknown/unrecorded age (not infants) and is grouped with nulls.
Sex Distribution (20,768 persons with recorded sex)
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-05-01 to 2021-05-31 · Person-level records linked to crash events
Speed Limit Zones
Crashes in 30 mph zones increased by 50.9% from 4,627 to 6,984, and the fatal rate in these zones rose from 0.173% to 0.215%. In 25 mph zones, crashes increased by 32.7% from 493 to 654, but the fatal rate decreased from 0.406% to 0.306%. The highest fatal crash rate in May 2021 was 1.786% in 45 mph zones, where 1 fatal crash occurred.
Fatal crashes by zone: 25 mph: 2 of 654 (0.306%) · 30 mph: 15 of 6,984 (0.215%) · 45 mph: 1 of 56 (1.786%)
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-05-01 to 2021-05-31 · Posted speed limit at crash location
Data Sources & Methodology
Primary Data Source
All crash data in this report is sourced from Chicago Traffic Crashes, accessed programmatically via the Socrata Open Data API (SODA). This dataset contains official police-reported motor vehicle traffic crash records maintained by the reporting jurisdiction's law enforcement agency. Records are published to the open data portal by the municipality and are subject to the portal's terms of use.
Data Retrieval
- Access method: Socrata Open Data API (SoQL queries)
- Data format: Structured JSON via REST API
- Record types queried: Crash events, person records, and vehicle unit records
- Date filter applied: 2021-05-01 through 2021-05-31
- Report generated: June 1, 2026
Data Coverage
- Reporting period: 2021-05-01 through 2021-05-31 (31 days)
- Geographic scope: Chicago, IL
- Total crash records analyzed: 9,651
- Total persons involved: 21,166
- Total vehicles involved: 19,848
Analytical Methodology
- Severity classification: Uses the KABCO injury scale (K=Fatal, A=Incapacitating injury, B=Non-incapacitating injury, C=Possible injury, O=No injury/property damage only), the standard classification in U.S. Model Minimum Uniform Crash Criteria (MMUCC). Severity is assigned per crash event based on the most severe injury in that crash. A single fatal crash (K) may involve multiple fatalities; therefore the "Persons Killed" count in the headline KPIs may differ from the "Fatal" crash count in the severity breakdown.
- Contributing factors: Reflect the officer-determined primary contributory cause recorded at the time of the crash report. These are preliminary determinations and may not reflect final investigation findings.
- Hit-and-run classification: Based on the hit-and-run indicator field in the official crash report, as determined by the responding officer at the scene.
- Temporal analysis: Day-of-week and hour-of-day distributions are computed from the crash date/time timestamp in each record.
- Demographics: Age and sex distributions are drawn from person-level records linked to each crash event. A single crash may involve multiple persons.
- Vehicle data: Make information is drawn from vehicle unit records linked to each crash event.
- AI commentary: Narrative sections are generated by Google Gemini (large language model) based on the structured data. Commentary is descriptive, not predictive, and should not be interpreted as expert opinion.
Limitations & Disclaimers
- Only crashes reported to and documented by law enforcement are included. Minor incidents, unreported crashes, and near-misses are not captured in this dataset.
- Data reflects conditions at the time of the initial police report and may be subject to subsequent corrections, reclassifications, or supplements by the reporting agency.
- Open data portal records may experience a publication lag - recently occurring crashes may not yet appear in the dataset at the time of report generation.
- AI-generated commentary is produced by a large language model and is intended to highlight patterns in the data. It does not constitute legal, medical, or professional analysis.
- Percentages are calculated from reported data and are subject to rounding.
Non-Affiliation Disclosure
This report is produced independently by ThatCarHitMe.com (Injuria.ai). It is not affiliated with, endorsed by, or produced in partnership with any law enforcement agency, municipal government, state department of transportation, or the National Highway Traffic Safety Administration (NHTSA). Data is sourced from publicly available government open data portals.
Data License
The underlying crash data is provided under the municipality's Open Data Terms of Use and is made available to the public for unrestricted use. This analysis and report is © 2026 Injuria.ai and may be cited with attribution using the suggested citation below.
Corrections & Feedback
If you believe any data in this report is inaccurate or have questions about our methodology, please contact: data@injuria.ai. We are committed to accuracy and will issue corrections promptly.
Suggested Citation
ThatCarHitMe.com (Injuria.ai). "Chicago, IL Crash Intelligence Report." Published June 1, 2026. Data source: Chicago Traffic Crashes, Socrata Open Data. Available at: https://thatcarhitme.com/crash-data/illinois/chicago/may-2021-report
About the Publisher
ThatCarHitMe.com is a crash data intelligence platform developed by Injuria.ai, a legal technology company specializing in traffic safety analytics. We aggregate and analyze publicly available government crash data to produce structured intelligence reports for communities, researchers, journalists, and legal professionals. Our reports combine programmatic data retrieval from official open data portals with AI-assisted narrative analysis.
Questions about this report's data or methodology: data@injuria.ai
ThatCarHitMe.com · An Injuria.ai Company
ThatCarHitMe.com
An Injuria.ai Company
Crash Data Intelligence
Data: Chicago Traffic Crashes · Socrata
Period: 2021-05-01 – 2021-05-31
Generated: June 1, 2026 · All rights reserved