ThatCarHitMe.com
An Injuria.ai Company
YEAR-OVER-YEAR CRASH REPORT · CHICAGO, IL · APRIL 2021
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/april-2021-report
Monthly Traffic Safety Analysis
8,169 CRASHES IN
CHICAGO, IL
APRIL 2021
Total crashes in April 2021 were 8,169, an 84.35% increase compared to 4,431 crashes in April 2020. Despite this significant rise in total crashes, the number of fatalities decreased by 53.85%, from 13 to 6, representing the most notable year-over-year shift in outcomes.
8,169
▲ 84.4%was 4,431
Total Crash Events
6
▼ -53.8%was 13
Persons Killed
1,800
▲ 99.3%was 903
Persons Injured
2,871
▲ 83.5%was 1,565
Hit-and-Run Crashes
Note: "Persons Killed" (6) counts individual fatalities across all crash events. "Fatal" in the severity table below (6) 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 · 2021-04-01 to 2021-04-30 · Aggregate counts from crash, person, and vehicle records
Trend Summary
Overall, crashes in April 2021 increased substantially compared to April 2020, with total crashes rising from 4,431 to 8,169, a change of 84.35%. This indicates a significant upward trend in crash incidents year-over-year.
2,871
Hit-and-Run Crashes — April 2021
▲ 83.5% vs prior (1,565)
Hit-and-run crashes increased significantly year-over-year, rising from 1,565 in April 2020 to 2,871 in April 2021, an 83.45% increase in count. Despite this rise in raw numbers, the hit-and-run crash rate remained relatively stable, decreasing slightly from 35.3% to 35.1% of all crashes.
Vulnerable Road User Casualties
2
Pedestrians Killed
0
Cyclists Killed
4
Motorists Killed
0
Other Killed
133
Pedestrians Injured
77
Cyclists Injured
1,588
Motorists Injured
2
Other Injured
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-04-01 to 2021-04-30 · 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 Wednesday in April 2020 (785 crashes) to Friday in April 2021 (1,480 crashes). The peak hour also changed from 2 PM in April 2020 (360 crashes) to 4 PM in April 2021 (674 crashes), both showing increased crash counts.
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-04-01 to 2021-04-30 · Crash date field aggregated by weekday
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-04-01 to 2021-04-30 · Crash time field aggregated by hour (0-23)
Crash Severity Breakdown
Fatalities decreased from 13 in April 2020 to 6 in April 2021, a 53.85% reduction. Conversely, total injuries nearly doubled, increasing by 99.33% from 903 to 1,800. The proportion of serious injury crashes (code 'A') decreased from 2.1% to 1.9%, while minor injury crashes (code 'B') increased from 7.9% to 9% of all crashes.
Outcome by Severity (Crash Events)
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-04-01 to 2021-04-30 · KABCO injury classification scale
Severity Distribution
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-04-01 to 2021-04-30 · Most severe injury per crash record
Top Contributing Factors
Among contributing factors, 'FAILING TO YIELD RIGHT-OF-WAY' increased from 460 to 807 crashes, a 75.43% rise in count. 'FOLLOWING TOO CLOSELY' also saw a substantial increase in count, from 354 to 679 crashes, marking a 91.81% change. 'FAILING TO REDUCE SPEED TO AVOID CRASH' increased by 27.33% in count, from 311 to 396 crashes.
Officer-Reported Primary Contributing Cause
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-04-01 to 2021-04-30 · Officer-reported primary contributory cause per crash
Road & Environmental Conditions
Crashes occurring in 'CLEAR' weather conditions more than doubled, increasing from 3,324 in April 2020 to 6,859 in April 2021, a 106.35% rise in count. Similarly, crashes on 'DRY' road surfaces increased from 3,273 to 6,721, a 105.33% increase in count. Crashes in 'RAIN' conditions saw a slight decrease in count from 636 to 614, a 3.46% reduction.
Weather
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-04-01 to 2021-04-30 · Weather condition at time of crash
Lighting
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-04-01 to 2021-04-30 · Lighting condition field
Road Surface
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-04-01 to 2021-04-30 · Road surface condition field
Vehicles & Demographics
The total number of vehicles involved in crashes increased from 9,189 to 16,663, an 81.35% rise. The number of 'DRIVER' type vehicles increased by 88.25% from 7,285 to 13,713, and 'PARKED' vehicles increased by 54.36% from 1,628 to 2,513. Among vehicle makes, CHEVROLET remained the most involved, increasing from 1,232 to 2,052 vehicles, a 66.56% increase.
Top Vehicle Makes (16,663 vehicles)
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-04-01 to 2021-04-30 · Vehicle unit records
5,535 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 (17,105 persons with recorded sex)
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-04-01 to 2021-04-30 · Person-level records linked to crash events
Speed Limit Zones
Crashes occurring in 30 mph speed zones increased from 3,134 to 5,890, an 88% rise in count. Fatal crashes within 30 mph zones decreased from 9 to 5, a 44.44% reduction. Crashes in 45 mph zones saw a substantial increase from 21 to 56, a 166.67% rise in count, with fatal crashes increasing from 0 to 1.
Fatal crashes by zone: 30 mph: 5 of 5,890 (0.085%) · 45 mph: 1 of 56 (1.786%)
Source: Chicago Traffic Crashes · Socrata Open Data · 2021-04-01 to 2021-04-30 · 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: 2021-04-01 through 2021-04-30
- Report generated: June 1, 2026
Data Coverage
- Reporting period: 2021-04-01 through 2021-04-30 (30 days)
- Geographic scope: Chicago, IL
- Total crash records analyzed: 8,169
- Total persons involved: 17,408
- Total vehicles involved: 16,663
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/april-2021-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: 2021-04-01 – 2021-04-30
Generated: June 1, 2026 · All rights reserved