ThatCarHitMe.com
An Injuria.ai Company
YEAR-OVER-YEAR CRASH REPORT · CHICAGO, IL · SEPTEMBER 2018
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-2018-report
Monthly Traffic Safety Analysis
9,931 CRASHES IN
CHICAGO, IL
SEPTEMBER 2018
In September 2018, Chicago experienced 9,931 total crashes, an increase of 9.9% compared to the 9,038 crashes reported in September 2017. Despite the rise in total incidents, total fatalities decreased by 30.8%, from 13 in the prior year to 9 in the current period. Total injuries saw a modest increase of 3.3%, rising from 1,897 to 1,959.
9,931
▲ 9.9%was 9,038
Total Crash Events
9
▼ -30.8%was 13
Persons Killed
1,959
▲ 3.3%was 1,897
Persons Injured
2,669
▲ 15.1%was 2,319
Hit-and-Run Crashes
Note: "Persons Killed" (9) counts individual fatalities across all crash events. "Fatal" in the severity table below (7) counts crash events where at least one fatality occurred. A single crash can result in multiple fatalities. 17 crashes with unreported severity are not shown in the severity breakdown.
Source: Chicago Traffic Crashes · Socrata Open Data · 2018-09-01 to 2018-09-30 · Aggregate counts from crash, person, and vehicle records
Trend Summary
Overall, crash incidents in Chicago are on an upward trend, with total crashes increasing by 9.9% year-over-year, from 9,038 to 9,931. Concurrently, total injuries also increased by 3.3%, from 1,897 to 1,959. However, a positive trend was observed in fatalities, which decreased by 30.8%, from 13 to 9.
2,669
Hit-and-Run Crashes — September 2018
▲ 15.1% vs prior (2,319)
Hit-and-run incidents increased year-over-year, rising from 2,319 crashes in September 2017 to 2,669 crashes in September 2018, an increase of 350 incidents. The hit-and-run rate also saw an upward trend, increasing from 25.7% of total crashes to 26.9%.
Vulnerable Road User Casualties
1
Pedestrians Killed
1
Cyclists Killed
7
Motorists Killed
259
Pedestrians Injured
176
Cyclists Injured
1,524
Motorists Injured
Source: Chicago Traffic Crashes · Socrata Open Data · 2018-09-01 to 2018-09-30 · 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 Friday in September 2017 (1,670 crashes) to Saturday in September 2018 (1,567 crashes), though both days saw a decrease in their respective peak counts. The peak hour for crashes remained consistently at 4 p.m. in both periods, with crashes at this hour increasing from 711 to 785. Notably, Sunday crashes significantly increased by 384, from 1,011 to 1,395.
Source: Chicago Traffic Crashes · Socrata Open Data · 2018-09-01 to 2018-09-30 · Crash date field aggregated by weekday
Source: Chicago Traffic Crashes · Socrata Open Data · 2018-09-01 to 2018-09-30 · Crash time field aggregated by hour (0-23)
Crash Severity Breakdown
The fatal crash rate decreased significantly from 0.13% in September 2017 to 0.07% in September 2018, with the number of fatal crashes dropping from 12 to 7. Serious injury crashes also saw a reduction, decreasing from 220 (2.4% share) to 190 (1.9% share). Conversely, minor injury crashes increased from 755 (8.4% share) to 840 (8.5% share), and no-injury crashes rose from 7,608 (84.2% share) to 8,468 (85.3% share).
Severity is per crash event (most severe injury). 7 fatal crash events resulted in 9 persons killed.
Outcome by Severity (Crash Events)
Source: Chicago Traffic Crashes · Socrata Open Data · 2018-09-01 to 2018-09-30 · KABCO injury classification scale
Severity Distribution
Source: Chicago Traffic Crashes · Socrata Open Data · 2018-09-01 to 2018-09-30 · Most severe injury per crash record
Top Contributing Factors
Failing to Yield Right-of-Way remained the leading contributing factor, increasing from 1,119 crashes in 2017 to 1,227 crashes in 2018, a rise of 108 incidents. Following Too Closely also maintained its second position, with counts increasing from 1,044 to 1,079 crashes, a change of 35 incidents. Improper Overtaking/Passing saw a notable increase of 100 crashes, rising from 396 to 496, which moved it into the third-highest ranking factor, displacing Improper Backing, which decreased by 24 crashes from 443 to 419.
Officer-Reported Primary Contributing Cause
Source: Chicago Traffic Crashes · Socrata Open Data · 2018-09-01 to 2018-09-30 · Officer-reported primary contributory cause per crash
Road & Environmental Conditions
A significant shift was observed in adverse weather conditions, with crashes occurring in rain increasing from 241 in 2017 to 853 in 2018, and cloudy/overcast conditions rising from 112 to 308. Correspondingly, crashes on wet road surfaces dramatically increased from 330 to 1,100 year-over-year. Crashes during daylight hours also increased, from 6,366 to 6,963.
Weather
Source: Chicago Traffic Crashes · Socrata Open Data · 2018-09-01 to 2018-09-30 · Weather condition at time of crash
Lighting
Source: Chicago Traffic Crashes · Socrata Open Data · 2018-09-01 to 2018-09-30 · Lighting condition field
Road Surface
Source: Chicago Traffic Crashes · Socrata Open Data · 2018-09-01 to 2018-09-30 · Road surface condition field
Vehicles & Demographics
The total number of vehicles involved in crashes increased from 18,548 in September 2017 to 20,218 in September 2018. The top three vehicle makes involved in crashes remained consistent, with Chevrolet, Toyota, and Ford holding the top spots, all showing an increase in counts. The age distribution of persons involved in crashes showed increases across all reported age groups, with the 35-44 age group seeing the largest increase of 389 persons, from 2,688 to 3,077.
Top Vehicle Makes (20,218 vehicles)
Source: Chicago Traffic Crashes · Socrata Open Data · 2018-09-01 to 2018-09-30 · Vehicle unit records
6,359 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 (22,040 persons with recorded sex)
Source: Chicago Traffic Crashes · Socrata Open Data · 2018-09-01 to 2018-09-30 · Person-level records linked to crash events
Speed Limit Zones
The 30 mph speed limit zone continued to account for the highest number of crashes, increasing from 6,666 in 2017 to 7,271 in 2018. Despite this increase in crashes, the fatal crash rate in the 30 mph zone decreased from 0.135% to 0.055%, with fatalities dropping from 9 to 4. The 35 mph zone also saw an increase in crashes, from 642 to 712, while its fatal crash rate slightly decreased from 0.312% to 0.281% with fatalities remaining at 2.
Fatal crashes by zone: 30 mph: 4 of 7,271 (0.055%) · 35 mph: 2 of 712 (0.281%)
Source: Chicago Traffic Crashes · Socrata Open Data · 2018-09-01 to 2018-09-30 · 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: 2018-09-01 through 2018-09-30
- Report generated: June 1, 2026
Data Coverage
- Reporting period: 2018-09-01 through 2018-09-30 (30 days)
- Geographic scope: Chicago, IL
- Total crash records analyzed: 9,931
- Total persons involved: 22,298
- Total vehicles involved: 20,218
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-2018-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: 2018-09-01 – 2018-09-30
Generated: June 1, 2026 · All rights reserved