ThatCarHitMe.com
An Injuria.ai Company
YEAR-OVER-YEAR CRASH REPORT · CHICAGO, IL · DECEMBER 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/december-2017-report
Monthly Traffic Safety Analysis
10,108 CRASHES IN
CHICAGO, IL
DECEMBER 2017
In December 2017, Chicago experienced 10,108 total crashes, a substantial increase from the 5,052 crashes recorded in December 2016, representing a 100.08% rise. The most significant year-over-year shift was in total fatalities, which surged from 1 in December 2016 to 9 in December 2017, an 800% increase.
10,108
▲ 100.1%was 5,052
Total Crash Events
9
▲ 800.0%was 1
Persons Killed
1,820
▲ 448.2%was 332
Persons Injured
2,691
▲ 99.9%was 1,346
Hit-and-Run Crashes
Note: "Persons Killed" (9) counts individual fatalities across all crash events. "Fatal" in the severity table below (9) 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 · 2017-12-01 to 2017-12-31 · Aggregate counts from crash, person, and vehicle records
Trend Summary
Overall, crash data for December 2017 indicates a significant upward trend compared to December 2016. Total crashes nearly doubled, increasing by 100.08% from 5,052 to 10,108. This suggests a substantial rise in traffic incidents within the city.
2,691
Hit-and-Run Crashes — December 2017
▲ 99.9% vs prior (1,346)
Hit-and-run crashes increased significantly in count, from 1,346 in December 2016 to 2,691 in December 2017, a 99.93% increase. Despite this rise in count, the hit-and-run rate remained stable at 26.6% for both periods.
Vulnerable Road User Casualties
0
Pedestrians Killed
2
Cyclists Killed
7
Motorists Killed
262
Pedestrians Injured
39
Cyclists Injured
1,519
Motorists Injured
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-12-01 to 2017-12-31 · 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 1,827 crashes in December 2017 compared to 927 in December 2016. The peak hour for crashes shifted from 3 PM with 435 crashes in December 2016 to 5 PM with 777 crashes in December 2017. Both the peak day and peak hour saw considerable increases in crash counts year-over-year.
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-12-01 to 2017-12-31 · Crash date field aggregated by weekday
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-12-01 to 2017-12-31 · Crash time field aggregated by hour (0-23)
Crash Severity Breakdown
The fatal crash rate increased from 0.02% in December 2016 to 0.09% in December 2017, with fatal crashes rising from 1 to 9. Serious injury crashes increased from 27 (0.5% share) to 183 (1.8% share), while minor injury crashes rose from 112 (2.2% share) to 682 (6.7% share). Conversely, the proportion of no-injury crashes decreased from 94.8% to 86.4% of all incidents.
Outcome by Severity (Crash Events)
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-12-01 to 2017-12-31 · KABCO injury classification scale
Severity Distribution
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-12-01 to 2017-12-31 · Most severe injury per crash record
Top Contributing Factors
The top contributing factor, 'FAILING TO YIELD RIGHT-OF-WAY,' increased from 467 crashes in December 2016 to 1,221 crashes in December 2017, a 161.46% increase. 'FOLLOWING TOO CLOSELY' also saw a significant rise, from 602 crashes to 1,152 crashes, an increase of 91.36%. 'FAILING TO REDUCE SPEED TO AVOID CRASH' experienced the largest percentage increase among top factors, rising by 212.41% from 145 crashes to 453 crashes, and moving from the 8th to the 3rd most common factor.
Officer-Reported Primary Contributing Cause
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-12-01 to 2017-12-31 · Officer-reported primary contributory cause per crash
Road & Environmental Conditions
Crashes occurring in 'CLEAR' weather conditions increased by 107.38% from 3,793 to 7,866, maintaining a similar share of total crashes (75.1% to 77.8%). Crashes in 'DARKNESS, LIGHTED ROAD' conditions saw a 136.41% increase, rising from 1,299 to 3,071, and their share of total crashes increased from 25.7% to 30.4%. Crashes on 'DRY' road surfaces increased by 131.25% from 3,044 to 7,039, with their share of total crashes increasing from 60.3% to 69.6%.
Weather
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-12-01 to 2017-12-31 · Weather condition at time of crash
Lighting
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-12-01 to 2017-12-31 · Lighting condition field
Road Surface
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-12-01 to 2017-12-31 · Road surface condition field
Vehicles & Demographics
The total number of vehicles involved in crashes increased by 103.02%, from 10,171 in December 2016 to 20,649 in December 2017. The ranking of top vehicle makes shifted, with Chevrolet moving from second to first place (1,208 to 2,364 crashes) and Toyota moving from first to second (1,223 to 2,345 crashes). The age groups most represented in crashes remained consistent, with 26-34, 35-44, and 45-54 being the highest for both periods.
Top Vehicle Makes (20,649 vehicles)
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-12-01 to 2017-12-31 · Vehicle unit records
6,358 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 (22,101 persons with recorded sex)
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-12-01 to 2017-12-31 · Person-level records linked to crash events
Speed Limit Zones
The 30 MPH speed zone continued to account for the highest number of crashes, increasing from 3,806 to 7,407 incidents, a 94.6% rise. Fatal crashes in the 30 MPH zone saw a 600% increase, rising from 1 to 7. Additionally, the 25 MPH and 35 MPH zones, which had no fatal crashes in December 2016, each recorded 1 fatal crash in December 2017.
Fatal crashes by zone: 25 mph: 1 of 600 (0.167%) · 30 mph: 7 of 7,407 (0.095%) · 35 mph: 1 of 795 (0.126%)
Source: Chicago Traffic Crashes · Socrata Open Data · 2017-12-01 to 2017-12-31 · 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: 2017-12-01 through 2017-12-31
- Report generated: June 1, 2026
Data Coverage
- Reporting period: 2017-12-01 through 2017-12-31 (31 days)
- Geographic scope: Chicago, IL
- Total crash records analyzed: 10,108
- Total persons involved: 22,377
- Total vehicles involved: 20,649
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/december-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: 2017-12-01 – 2017-12-31
Generated: June 1, 2026 · All rights reserved