ThatCarHitMe.com
An Injuria.ai Company
YEAR-OVER-YEAR CRASH REPORT · CHICAGO, IL · SEPTEMBER 2020
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/september-2020-report
Monthly Traffic Safety Analysis
8,286 CRASHES IN
CHICAGO, IL
SEPTEMBER 2020
Total crashes in Chicago decreased by 15.6% year-over-year, from 9815 in September 2019 to 8286 in September 2020. The most notable year-over-year shift was the significant increase in the hit-and-run crash rate, which rose from 27.4% to 34.6% of all crashes.
8,286
▼ -15.6%was 9,815
Total Crash Events
16
▲ 33.3%was 12
Persons Killed
1,872
▼ -5.8%was 1,987
Persons Injured
2,871
▲ 6.9%was 2,686
Hit-and-Run Crashes
Note: "Persons Killed" (16) counts individual fatalities across all crash events. "Fatal" in the severity table below (14) counts crash events where at least one fatality occurred. A single crash can result in multiple fatalities. 20 crashes with unreported severity are not shown in the severity breakdown.
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-09-01 to 2020-09-30 · Aggregate counts from crash, person, and vehicle records
Trend Summary
Overall, crash incidents in Chicago decreased by 15.6% from September 2019 to September 2020, dropping from 9815 to 8286 crashes. Despite this reduction, total fatalities increased by 33.3%, rising from 12 to 16 individuals. Concurrently, total injuries saw a modest decrease of 5.8%, from 1987 to 1872.
2,871
Hit-and-Run Crashes — September 2020
▲ 6.9% vs prior (2,686)
Hit-and-run crashes increased by 185 incidents, rising from 2686 in September 2019 to 2871 in September 2020. This represents a 6.9% increase in the number of hit-and-run crashes. The hit-and-run rate also increased significantly, from 27.4% of all crashes in the prior period to 34.6% in the current period, an increase of 7.2 percentage points.
Vulnerable Road User Casualties
2
Pedestrians Killed
1
Cyclists Killed
13
Motorists Killed
0
Other Killed
167
Pedestrians Injured
144
Cyclists Injured
1,557
Motorists Injured
4
Other Injured
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-09-01 to 2020-09-30 · 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 Monday in September 2019 (1550 crashes) to Tuesday in September 2020 (1295 crashes). The peak hour for crashes remained 4 PM in both periods, although the count decreased from 723 crashes in the prior period to 695 crashes in the current period. Crashes on Sundays, Mondays, and Fridays saw significant decreases, with Monday crashes dropping by 32.8% from 1550 to 1041.
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-09-01 to 2020-09-30 · Crash date field aggregated by weekday
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-09-01 to 2020-09-30 · Crash time field aggregated by hour (0-23)
Crash Severity Breakdown
The number of fatal crashes increased from 12 in September 2019 to 14 in September 2020, representing a 16.7% rise. Consequently, the fatal crash rate increased from 0.12% to 0.17% year-over-year. While serious, minor, and possible injury crashes all decreased in count, the total number of fatalities rose from 12 to 16, a 33.3% increase.
Severity is per crash event (most severe injury). 14 fatal crash events resulted in 16 persons killed.
Outcome by Severity (Crash Events)
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-09-01 to 2020-09-30 · KABCO injury classification scale
Severity Distribution
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-09-01 to 2020-09-30 · Most severe injury per crash record
Top Contributing Factors
Most top contributing factors saw a decrease in count, consistent with the overall reduction in crashes. 'FAILING TO YIELD RIGHT-OF-WAY' decreased by 253 crashes (-23.5%), and 'FOLLOWING TOO CLOSELY' decreased by 265 crashes (-26.5%). Notably, 'DISREGARDING TRAFFIC SIGNALS' increased by 47 crashes (+28.1%), rising from 167 to 214, and crashes attributed to 'HAD BEEN DRINKING' increased by 33.3%, from 9 to 12.
Officer-Reported Primary Contributing Cause
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-09-01 to 2020-09-30 · Officer-reported primary contributory cause per crash
Road & Environmental Conditions
Crashes occurring in 'CLEAR' weather conditions decreased by 826, from 7709 to 6883, while crashes in 'RAIN' decreased by 524, from 1304 to 780. Crashes on 'DRY' road surfaces decreased by 766, from 7546 to 6780, and on 'WET' surfaces by 650, from 1613 to 963. While most conditions saw fewer associated crashes, crashes occurring in 'DARKNESS' (unlighted roads) increased by 12, from 376 to 388.
Weather
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-09-01 to 2020-09-30 · Weather condition at time of crash
Lighting
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-09-01 to 2020-09-30 · Lighting condition field
Road Surface
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-09-01 to 2020-09-30 · Road surface condition field
Vehicles & Demographics
The total number of vehicles involved in crashes decreased by 15.1%, from 20130 to 17093. The number of persons involved in crashes decreased by 20.8%, from 22233 to 17599, with all age groups experiencing a reduction in involvement. A notable shift was observed in sex distribution, where male involvement decreased by 20.5% and female involvement by 26.1%, while 'Non-Binary' involvement increased by 6.2%, from 1683 to 1787.
Top Vehicle Makes (17,093 vehicles)
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-09-01 to 2020-09-30 · Vehicle unit records
5,415 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 (17,351 persons with recorded sex)
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-09-01 to 2020-09-30 · Person-level records linked to crash events
Speed Limit Zones
The 30 mph speed limit zone remained the location for the highest number of crashes, though the count decreased from 7167 to 6033 (-15.8%). The fatal crash rate in the 30 mph zone increased from 0.084% to 0.133%. A significant change occurred in the 40 mph zone, where fatal crashes increased from 0 to 2, resulting in a fatal rate of 2.299% compared to 0% in the prior period.
Fatal crashes by zone: 25 mph: 2 of 526 (0.38%) · 30 mph: 8 of 6,033 (0.133%) · 35 mph: 2 of 643 (0.311%) · 40 mph: 2 of 87 (2.299%)
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-09-01 to 2020-09-30 · 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: 2020-09-01 through 2020-09-30
- Report generated: June 1, 2026
Data Coverage
- Reporting period: 2020-09-01 through 2020-09-30 (30 days)
- Geographic scope: Chicago, IL
- Total crash records analyzed: 8,286
- Total persons involved: 17,599
- Total vehicles involved: 17,093
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/september-2020-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: 2020-09-01 – 2020-09-30
Generated: June 1, 2026 · All rights reserved