ThatCarHitMe.com
An Injuria.ai Company
YEAR-OVER-YEAR CRASH REPORT · CHICAGO, IL · DECEMBER 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/december-2020-report
Monthly Traffic Safety Analysis
7,254 CRASHES IN
CHICAGO, IL
DECEMBER 2020
Total crashes in December 2020 decreased by 23.0% to 7,254, down from 9,418 crashes in December 2019. Despite this overall reduction in crashes, total fatalities increased significantly by 200.0%, rising from 5 to 15. The number of fatal crashes also saw a substantial increase, climbing from 5 to 13, representing a 160.0% rise year-over-year.
7,254
▼ -23.0%was 9,418
Total Crash Events
15
▲ 200.0%was 5
Persons Killed
1,366
▼ -16.7%was 1,640
Persons Injured
2,561
▼ -4.3%was 2,675
Hit-and-Run Crashes
Note: "Persons Killed" (15) counts individual fatalities across all crash events. "Fatal" in the severity table below (13) counts crash events where at least one fatality occurred. A single crash can result in multiple fatalities. 26 crashes with unreported severity are not shown in the severity breakdown.
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-12-01 to 2020-12-31 · Aggregate counts from crash, person, and vehicle records
Trend Summary
Overall, crashes in Chicago experienced a downward trend year-over-year, with a 23.0% decrease in total crashes, from 9,418 in December 2019 to 7,254 in December 2020. Despite this reduction, total fatalities increased from 5 to 15, indicating a concerning rise in the severity of crashes.
2,561
Hit-and-Run Crashes — December 2020
▼ -4.3% vs prior (2,675)
The total number of hit-and-run crashes decreased by 114, from 2,675 in December 2019 to 2,561 in December 2020. However, the hit-and-run rate, as a percentage of total crashes, increased by 6.9 percentage points, rising from 28.4% to 35.3%.
Vulnerable Road User Casualties
6
Pedestrians Killed
0
Cyclists Killed
9
Motorists Killed
0
Other Killed
125
Pedestrians Injured
32
Cyclists Injured
1,207
Motorists Injured
2
Other Injured
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-12-01 to 2020-12-31 · 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 Tuesday in both periods, though the count decreased from 1,582 in December 2019 to 1,240 in December 2020. Similarly, the peak hour for crashes remained 5 PM, with counts decreasing from 723 to 683 year-over-year. Crashes on Wednesday notably increased by 50, from 1,125 to 1,175, while all other days of the week experienced decreases.
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-12-01 to 2020-12-31 · Crash date field aggregated by weekday
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-12-01 to 2020-12-31 · Crash time field aggregated by hour (0-23)
Crash Severity Breakdown
The fatal crash rate increased from 0.1% of total crashes in December 2019 to 0.2% in December 2020. The number of serious injury crashes decreased by 19, from 158 to 139, while minor injury crashes decreased by 157, from 693 to 536. Possible injury crashes also saw a decrease of 38, from 358 to 320, though their share of total crashes increased from 3.8% to 4.4%.
Severity is per crash event (most severe injury). 13 fatal crash events resulted in 15 persons killed.
Outcome by Severity (Crash Events)
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-12-01 to 2020-12-31 · KABCO injury classification scale
Severity Distribution
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-12-01 to 2020-12-31 · Most severe injury per crash record
Top Contributing Factors
The top contributing factors, 'FAILING TO YIELD RIGHT-OF-WAY' and 'FOLLOWING TOO CLOSELY,' both decreased in count, by 375 crashes (-34.5%) and 370 crashes (-38.1%) respectively. 'FAILING TO REDUCE SPEED TO AVOID CRASH' also decreased by 124 crashes (-25.8%). Conversely, 'WEATHER' as a contributing factor saw a substantial increase of 99 crashes (+105.3%), rising from 94 to 193.
Officer-Reported Primary Contributing Cause
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-12-01 to 2020-12-31 · Officer-reported primary contributory cause per crash
Road & Environmental Conditions
Crashes occurring in 'CLEAR' weather conditions decreased by 2,378, from 7,862 to 5,484. However, crashes during 'RAIN' increased by 159 (+33.8%) and during 'SNOW' increased by 151 (+52.6%). Similarly, crashes on 'SNOW OR SLUSH' road surfaces increased by 204 (+89.1%), indicating a shift towards more adverse weather-related incidents.
Weather
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-12-01 to 2020-12-31 · Weather condition at time of crash
Lighting
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-12-01 to 2020-12-31 · Lighting condition field
Road Surface
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-12-01 to 2020-12-31 · Road surface condition field
Vehicles & Demographics
The total number of vehicles involved in crashes decreased by 4,702, a 24.2% reduction, from 19,439 to 14,737. The top vehicle makes involved in crashes generally saw decreases in their counts, with Chevrolet decreasing by 403 and Toyota by 708. The relative ranking of the top vehicle makes remained largely consistent between the two periods.
Top Vehicle Makes (14,737 vehicles)
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-12-01 to 2020-12-31 · Vehicle unit records
4,651 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 (15,064 persons with recorded sex)
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-12-01 to 2020-12-31 · Person-level records linked to crash events
Speed Limit Zones
Crashes in the 30 mph speed limit zone decreased by 1,660, from 6,964 to 5,304, but the fatal rate in this zone increased from 0.029% to 0.17%. The 25 mph zone saw a decrease of 115 crashes, from 572 to 457, with its fatal rate decreasing from 0.35% to 0.219%. Notably, the 10 mph and 20 mph zones, which had 0 fatal crashes in December 2019, each recorded 1 fatal crash in December 2020.
Fatal crashes by zone: 10 mph: 1 of 205 (0.488%) · 20 mph: 1 of 303 (0.33%) · 25 mph: 1 of 457 (0.219%) · 30 mph: 9 of 5,304 (0.17%) · 35 mph: 1 of 564 (0.177%)
Source: Chicago Traffic Crashes · Socrata Open Data · 2020-12-01 to 2020-12-31 · 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: 2020-12-01 through 2020-12-31
- Report generated: June 1, 2026
Data Coverage
- Reporting period: 2020-12-01 through 2020-12-31 (31 days)
- Geographic scope: Chicago, IL
- Total crash records analyzed: 7,254
- Total persons involved: 15,301
- Total vehicles involved: 14,737
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-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: 2020-12-01 – 2020-12-31
Generated: June 1, 2026 · All rights reserved