ThatCarHitMe.com
An Injuria.ai Company
YEAR-OVER-YEAR CRASH REPORT · CHICAGO, IL · SEPTEMBER 2017
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-2017-report
Monthly Traffic Safety Analysis
9,038 CRASHES IN
CHICAGO, IL
SEPTEMBER 2017
In September 2017, Chicago experienced 9,038 total crashes, marking a substantial 91.93% increase compared to the 4,709 crashes recorded in September 2016. The most significant year-over-year shift was the rise in total fatalities from 0 in the prior period to 13 in the current period.
9,038
▲ 91.9%was 4,709
Total Crash Events
13
Persons Killed
1,897
▲ 333.1%was 438
Persons Injured
2,319
▲ 101.1%was 1,153
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. 11 crashes with unreported severity are not shown in the severity breakdown.
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-09-01 to 2017-09-30 · Aggregate counts from crash, person, and vehicle records
Trend Summary
Overall, crash incidents in Chicago showed a significant upward trend year-over-year, with total crashes increasing by 91.93% from 4,709 to 9,038. This increase was also reflected in total injuries, which rose by 333.1% from 438 to 1,897.
2,319
Hit-and-Run Crashes — September 2017
▲ 101.1% vs prior (1,153)
Hit-and-run crashes increased by 101.13% in count, from 1,153 to 2,319 incidents year-over-year. The hit-and-run rate also saw a slight increase, rising from 24.5% of all crashes in September 2016 to 25.7% in September 2017.
Vulnerable Road User Casualties
2
Pedestrians Killed
0
Cyclists Killed
11
Motorists Killed
0
Other Killed
243
Pedestrians Injured
211
Cyclists Injured
1,442
Motorists Injured
1
Other Injured
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-09-01 to 2017-09-30 · Mode classified from person records (driver/passenger → motorist; pedestrian; bicyclist → cyclist; in-line skater / unspecified → other)
When Crashes Happen
The peak day for crashes remained Friday in both periods, with 1,670 crashes in September 2017 compared to 896 in September 2016. The peak hour for crashes shifted from 3 PM with 426 incidents in the prior period to 4 PM with 711 incidents in the current period.
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-09-01 to 2017-09-30 · Crash date field aggregated by weekday
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-09-01 to 2017-09-30 · Crash time field aggregated by hour (0-23)
Crash Severity Breakdown
The fatal crash rate increased from 0% in September 2016 to 0.13% in September 2017, corresponding to 0 fatal crashes versus 12 fatal crashes, respectively. The proportion of crashes resulting in any injury (Serious, Minor, or Possible) rose from 6.58% in the prior period to 15.57% in the current period.
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 · 2017-09-01 to 2017-09-30 · KABCO injury classification scale
Severity Distribution
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-09-01 to 2017-09-30 · Most severe injury per crash record
Top Contributing Factors
The leading contributing factor, 'FAILING TO YIELD RIGHT-OF-WAY', saw its count increase from 447 to 1,119, a 150.34% rise, and moved from second to first in ranking. 'FOLLOWING TOO CLOSELY' increased by 58.18% in count, from 660 to 1,044, shifting from first to second place among factors.
Officer-Reported Primary Contributing Cause
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-09-01 to 2017-09-30 · Officer-reported primary contributory cause per crash
Road & Environmental Conditions
The proportion of crashes occurring in 'CLEAR' weather conditions increased from 84.7% to 93.2% year-over-year, while crashes in 'RAIN' decreased proportionally from 8.1% to 2.7%. Similarly, crashes on 'DRY' road surfaces increased from 82.3% to 91.5%, with 'WET' road surface crashes decreasing proportionally from 10.4% to 3.6%.
Weather
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-09-01 to 2017-09-30 · Weather condition at time of crash
Lighting
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-09-01 to 2017-09-30 · Lighting condition field
Road Surface
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-09-01 to 2017-09-30 · Road surface condition field
Vehicles & Demographics
The total number of vehicles involved in crashes increased by 95.49%, from 9,488 to 18,548. The top three vehicle makes involved in crashes remained Chevrolet, Toyota, and Ford, all experiencing significant increases in counts: Chevrolet by 75.81%, Toyota by 88.51%, and Ford by 94.82%.
Top Vehicle Makes (18,548 vehicles)
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-09-01 to 2017-09-30 · Vehicle unit records
5,652 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 (19,913 persons with recorded sex)
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-09-01 to 2017-09-30 · Person-level records linked to crash events
Speed Limit Zones
Fatalities within specific speed zones were recorded in the current period, with 1 fatal crash at 25 mph, 9 at 30 mph, and 2 at 35 mph, whereas no fatalities were recorded in any speed zone in the prior period. Crash counts increased across all common speed zones, with 35 mph zones seeing the largest percentage increase in crashes, rising by 176.72% from 232 to 642 incidents.
Fatal crashes by zone: 25 mph: 1 of 543 (0.184%) · 30 mph: 9 of 6,666 (0.135%) · 35 mph: 2 of 642 (0.312%)
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-09-01 to 2017-09-30 · 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: 2017-09-01 through 2017-09-30
- Report generated: June 1, 2026
Data Coverage
- Reporting period: 2017-09-01 through 2017-09-30 (30 days)
- Geographic scope: Chicago, IL
- Total crash records analyzed: 9,038
- Total persons involved: 20,143
- Total vehicles involved: 18,548
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-2017-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: 2017-09-01 – 2017-09-30
Generated: June 1, 2026 · All rights reserved