ThatCarHitMe.com
An Injuria.ai Company
YEAR-OVER-YEAR CRASH REPORT · CHICAGO, IL · OCTOBER 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/october-2021-report
Monthly Traffic Safety Analysis
10,275 CRASHES IN
CHICAGO, IL
OCTOBER 2021
Total crashes in October 2021 increased to 10275, a 23.0% rise compared to 8354 crashes in October 2020. Despite this increase in overall crash volume, total fatalities decreased by 23.5%, from 17 to 13. This suggests a notable shift towards less severe outcomes in a higher volume of incidents.
10,275
▲ 23.0%was 8,354
Total Crash Events
13
▼ -23.5%was 17
Persons Killed
2,115
▲ 15.4%was 1,832
Persons Injured
3,359
▲ 17.2%was 2,867
Hit-and-Run Crashes
Note: "Persons Killed" (13) counts individual fatalities across all crash events. "Fatal" in the severity table below (12) counts crash events where at least one fatality occurred. A single crash can result in multiple fatalities. 28 crashes with unreported severity are not shown in the severity breakdown.
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-10-01 to 2021-10-31 · Aggregate counts from crash, person, and vehicle records
Trend Summary
Overall crash data for October 2021 indicates a rising trend in total incidents, with crashes increasing by 23.0% from 8354 to 10275 year-over-year. Total injuries also increased by 15.5%, rising from 1832 to 2115 persons. Conversely, total fatalities decreased by 23.5%, falling from 17 to 13 persons.
3,359
Hit-and-Run Crashes — October 2021
▲ 17.2% vs prior (2,867)
Hit-and-run crashes increased in absolute count from 2867 in October 2020 to 3359 in October 2021, a rise of 492 incidents. However, the hit-and-run rate, as a percentage of total crashes, decreased from 34.3% to 32.7% year-over-year. This indicates a slight downward trend in the proportion of crashes that are hit-and-runs.
Vulnerable Road User Casualties
5
Pedestrians Killed
0
Cyclists Killed
8
Motorists Killed
0
Other Killed
242
Pedestrians Injured
132
Cyclists Injured
1,740
Motorists Injured
1
Other Injured
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-10-01 to 2021-10-31 · Mode classified from person records (driver/passenger → motorist; pedestrian; bicyclist → cyclist; in-line skater / unspecified → other)
When Crashes Happen
The peak day for crashes remained Friday in both periods, with 1978 crashes in October 2021 compared to 1506 in October 2020. The peak hour shifted from 4 p.m. in October 2020 (680 crashes) to 3 p.m. in October 2021 (839 crashes). All days of the week experienced an increase in crash counts year-over-year.
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-10-01 to 2021-10-31 · Crash date field aggregated by weekday
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-10-01 to 2021-10-31 · Crash time field aggregated by hour (0-23)
Crash Severity Breakdown
The fatal crash rate decreased from 0.18% of total crashes in October 2020 to 0.12% in October 2021, with the number of fatal crashes dropping from 15 to 12. While the absolute number of minor and possible injuries increased, the proportion of serious, minor, and possible injury crashes slightly decreased relative to total crashes. Crashes resulting in no injury increased in count from 7011 to 8684, and also increased as a proportion of total crashes from 83.9% to 84.5%.
Severity is per crash event (most severe injury). 12 fatal crash events resulted in 13 persons killed.
Outcome by Severity (Crash Events)
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-10-01 to 2021-10-31 · KABCO injury classification scale
Severity Distribution
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-10-01 to 2021-10-31 · Most severe injury per crash record
Top Contributing Factors
The top two contributing factors, 'FAILING TO YIELD RIGHT-OF-WAY' and 'FOLLOWING TOO CLOSELY', maintained their ranks and saw increases in crash counts. 'FAILING TO YIELD RIGHT-OF-WAY' crashes increased by 249 (27.9%) from 894 to 1143, while 'FOLLOWING TOO CLOSELY' crashes rose by 125 (16.7%) from 748 to 873. 'IMPROPER OVERTAKING/PASSING' moved into the third rank, increasing by 120 crashes (32.1%) from 374 to 494.
Officer-Reported Primary Contributing Cause
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-10-01 to 2021-10-31 · Officer-reported primary contributory cause per crash
Road & Environmental Conditions
Crashes occurring during rainy weather significantly increased, rising from 1100 incidents in October 2020 to 2098 in October 2021. Similarly, crashes on wet road surfaces also saw a substantial increase from 1457 to 2477. In contrast, crashes during snowy conditions decreased from 47 to 6 incidents year-over-year.
Weather
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-10-01 to 2021-10-31 · Weather condition at time of crash
Lighting
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-10-01 to 2021-10-31 · Lighting condition field
Road Surface
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-10-01 to 2021-10-31 · Road surface condition field
Vehicles & Demographics
The total number of vehicles involved in crashes increased from 17171 to 21028 year-over-year. Chevrolet remained the most frequently involved vehicle make, with its count rising from 2143 to 2431. Toyota moved to the second position, increasing its involvement from 1559 to 2113, while Ford dropped to third, despite an increase in its crash count from 1731 to 2101.
Top Vehicle Makes (21,028 vehicles)
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-10-01 to 2021-10-31 · Vehicle unit records
7,071 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 (22,062 persons with recorded sex)
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-10-01 to 2021-10-31 · Person-level records linked to crash events
Speed Limit Zones
The majority of crashes in both periods occurred in the 30 mph speed zone, which saw an increase from 6041 to 7675 crashes. However, the fatal crash rate within the 30 mph zone decreased from 0.248% to 0.143%. The 25 mph zone experienced an increase in crashes from 576 to 673, and recorded one fatal crash in October 2021 compared to zero in October 2020.
Fatal crashes by zone: 25 mph: 1 of 673 (0.149%) · 30 mph: 11 of 7,675 (0.143%)
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-10-01 to 2021-10-31 · 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: 2021-10-01 through 2021-10-31
- Report generated: June 1, 2026
Data Coverage
- Reporting period: 2021-10-01 through 2021-10-31 (31 days)
- Geographic scope: Chicago, IL
- Total crash records analyzed: 10,275
- Total persons involved: 22,396
- Total vehicles involved: 21,028
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/october-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: 2021-10-01 – 2021-10-31
Generated: June 1, 2026 · All rights reserved