Monthly Traffic Safety Analysis

5,115 CRASHES IN
IOWA, IA
DECEMBER 2018

All metrics benchmarked againstDecember 2017

In December 2018, Iowa recorded 5,115 traffic crashes, a 13.2% decrease from the 5,895 crashes reported in December 2017. While total fatalities remained unchanged at 26, total injuries fell by 14.4% from 1,742 to 1,492. The most notable year-over-year shift was a significant reduction in crashes attributed to adverse winter weather, with incidents on snow-covered roads dropping from 1,224 in 2017 to 227 in 2018.

5,115

▼ -13.2%was 5,895

Total Crash Events

26

Persons Killed

1,492

▼ -14.4%was 1,742

Persons Injured

22

▼ -8.3%was 24

Fatal Crash Events

Note: "Persons Killed" (26) counts individual fatalities across all crash events. "Fatal" in the severity table below (22) counts crash events where at least one fatality occurred. A single crash can result in multiple fatalities.

Source: Iowa Crash Data · ArcGIS Open Data · 2018-12-01 to 2018-12-31 · Aggregate counts from crash, person, and vehicle records

Trend Summary

Traffic crashes across Iowa saw a notable downward trend in December 2018 compared to the same month in the prior year. Total collisions decreased by 13.2%, from 5,895 to 5,115. This decline was accompanied by a 14.4% drop in injuries, although the number of fatalities held steady at 26 in both periods.

Vulnerable Road User Casualties

0

Pedestrians Killed

Prior: 3↓-100.0%

0

Cyclists Killed

Prior: 0→0.0%

26

Motorists Killed

Prior: 23↑13.0%

36

Pedestrians Injured

Prior: 35↑2.9%

9

Cyclists Injured

Prior: 9→0.0%

1,447

Motorists Injured

Prior: 1,697↓-14.7%

Source: Iowa Crash Data · ArcGIS Open Data · 2018-12-01 to 2018-12-31 · Mode classified from person records (driver/passenger → motorist; pedestrian; bicyclist → cyclist; in-line skater / unspecified → other)

When Crashes Happen

The temporal patterns of crashes remained consistent year-over-year, with Friday being the peak day for collisions and 5 p.m. being the peak hour in both December 2017 and December 2018. However, the volume of crashes on the peak day decreased from 1,367 in the prior year to 918 in the current period. The number of crashes during the 5 p.m. peak hour was identical in both periods at 610.

Source: Iowa Crash Data · ArcGIS Open Data · 2018-12-01 to 2018-12-31 · Crash date field aggregated by weekday

Source: Iowa Crash Data · ArcGIS Open Data · 2018-12-01 to 2018-12-31 · Crash time field aggregated by hour (0-23)

Crash Severity Breakdown

The severity distribution of crashes remained relatively stable between the two periods. The fatal crash rate saw a minor increase from 0.41% of all crashes in December 2017 to 0.43% in December 2018, even as the absolute number of fatal crashes fell from 24 to 22. The combined share of all injury-related crashes (Serious, Minor, and Possible) was 25.0% in the current period, a slight increase from 24.3% in the prior period.

Severity is per crash event (most severe injury). 22 fatal crash events resulted in 26 persons killed.

Outcome by Severity (Crash Events)

Fatal22fatal crashes0.4%
↓-8.3%prior 24
Serious Injury76serious injury crashes1.5%
↓-12.6%prior 87
Minor Injury387minor injury crashes7.6%
↓-9.4%prior 427
Possible Injury811possible injury crashes15.9%
↓-12.0%prior 922
No Injury3,819no injury crashes74.7%
↓-13.9%prior 4,435

Source: Iowa Crash Data · ArcGIS Open Data · 2018-12-01 to 2018-12-31 · KABCO injury classification scale

Severity Distribution (Crash Events)

Source: Iowa Crash Data · ArcGIS Open Data · 2018-12-01 to 2018-12-31 · Most severe injury per crash record

Top Contributing Factors

In December 2018, the top three contributing factors were collisions with an animal (797 crashes), followed too close (493), and driving too fast for conditions (404). Compared to December 2017, crashes involving an animal remained the top factor, with the count increasing by 2.7% from 776. The most significant change was a 40.1% decrease in the count of crashes for 'driving too fast for conditions,' which fell from 675 to 404, dropping it from the second to the third-ranked cause.

Officer-Reported Primary Contributing Cause

Animal797 (15.6%)↑2.7%prior 776
Followed too close493 (9.6%)↓-9.2%prior 543
Driving too fast for conditions404 (7.9%)↓-40.1%prior 675
Ran off road - left366 (7.2%)↓-23.8%prior 480
Lost Control287 (5.6%)↓-30.8%prior 415
FTYROW: From stop sign257 (5%)↑5.3%prior 244
Other (explain in narrative): Other250 (4.9%)↓-32.2%prior 369
FTYROW: Making left turn202 (3.9%)↓-13.3%prior 233
Ran off road - straight201 (3.9%)↓-24.7%prior 267
Ran Stop Sign145 (2.8%)↓-8.8%prior 159

Source: Iowa Crash Data · ArcGIS Open Data · 2018-12-01 to 2018-12-31 · Officer-reported primary contributory cause per crash

Road & Environmental Conditions

A significant shift in environmental conditions was observed between the two periods. In December 2018, crashes on snow-covered roads fell sharply to 227 from 1,224 in the prior year, and crashes in snowy weather dropped from 867 to 264. Conversely, crashes on icy or frosty surfaces increased from 473 to 653. Lighting conditions for crashes showed a similar distribution, with daylight remaining the most common condition in both periods, though the count of such crashes decreased from 2,946 to 2,381.

Weather

Clear2,443 (54.8%)
↓-17.8%prior 2,973
Cloudy946 (21.2%)
↓-13.9%prior 1,099
Freezing rain/drizzle363 (8.1%)
↑197.5%prior 122
Rain303 (6.8%)
↑332.9%prior 70
Snow264 (5.9%)
↓-69.6%prior 867
Fog, smoke, smog69 (1.5%)
↑590.0%prior 10
Blowing Snow38 (0.9%)
↓-53.7%prior 82
Sleet, hail23 (0.5%)
↑228.6%prior 7
Other (explain in narrative)6 (0.1%)
↓-53.8%prior 13
Severe Winds2 (0.0%)
↓-90.9%prior 22

Source: Iowa Crash Data · ArcGIS Open Data · 2018-12-01 to 2018-12-31 · Weather condition at time of crash

Lighting

Daylight2,381 (53.3%)
↓-19.2%prior 2,946
Dark - roadway lighted1,049 (23.5%)
↓-11.3%prior 1,182
Dark - roadway not lighted712 (15.9%)
↓-13.1%prior 819
Dusk154 (3.4%)
↓-21.8%prior 197
Dawn146 (3.3%)
↑28.1%prior 114
Dark - unknown roadway lighting27 (0.6%)
↓-12.9%prior 31

Source: Iowa Crash Data · ArcGIS Open Data · 2018-12-01 to 2018-12-31 · Lighting condition field

Road Surface

Dry2,662 (59.7%)
↓-12.9%prior 3,056
Wet771 (17.3%)
↑142.5%prior 318
Ice/frost653 (14.6%)
↑38.1%prior 473
Snow227 (5.1%)
↓-81.5%prior 1,224
Slush81 (1.8%)
↓-28.9%prior 114
Gravel49 (1.1%)
↓-38.0%prior 79
Other (explain in narrative)10 (0.2%)
→0.0%prior 10
Mud, dirt7 (0.2%)
Water (standing or moving)1 (0.0%)
Sand1 (0.0%)

Source: Iowa Crash Data · ArcGIS Open Data · 2018-12-01 to 2018-12-31 · Road surface condition field

Vehicles & Demographics

The top vehicle makes involved in crashes, including Ford, Chevrolet, and Dodge, remained consistent between December 2017 and December 2018, with counts for each decreasing in line with the overall trend. The age distribution of persons involved in crashes also showed no significant year-over-year shifts. For instance, the 26-34 age group represented 15.4% of persons in the current period, compared to 16.0% in the prior period.

Top Vehicle Makes (8,568 vehicles)

1
FORD1,483 (17.3%)
↓-5.8%prior 1,574
2
CHEV1,192 (13.9%)
↓-13.3%prior 1,375
3
CHEVROLET485 (5.7%)
↓-23.6%prior 635
4
DODG423 (4.9%)
↓-2.1%prior 432
5
TOYT391 (4.6%)
↓-20.9%prior 494
6
JEEP307 (3.6%)
↓-11.3%prior 346
7
GMC289 (3.4%)
↓-5.2%prior 305
8
HOND271 (3.2%)
↓-13.1%prior 312
9
NISS246 (2.9%)
→0.0%prior 246
10
NR223 (2.6%)
↓-5.9%prior 237

Source: Iowa Crash Data · ArcGIS Open Data · 2018-12-01 to 2018-12-31 · Vehicle unit records

1,054 persons with unknown or unrecorded age excluded from age chart.

Sex Distribution (5,601 persons with recorded sex)

Male3,139 (56.0%)
↓-19.3%prior 3,891
Female2,462 (44.0%)
↓-14.0%prior 2,862

Source: Iowa Crash Data · ArcGIS Open Data · 2018-12-01 to 2018-12-31 · Person-level records linked to crash events

Data Sources & Methodology

Primary Data Source

All crash data in this report is sourced from Iowa Crash Data, accessed programmatically via the ArcGIS 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: ArcGIS 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: 2018-12-01 through 2018-12-31
  • Report generated: September 9, 2026

Data Coverage

  • Reporting period: 2018-12-01 through 2018-12-31 (31 days)
  • Geographic scope: iowa, IA
  • Total crash records analyzed: 5,115
  • Total persons involved: 8,917
  • Total vehicles involved: 8,568

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). "iowa, IA Crash Intelligence Report: December 2018." Published September 9, 2026. Reporting period: 2018-12-01 to 2018-12-31. Data source: Iowa Crash Data, ArcGIS Open Data. Available at: https://thatcarhitme.com/crash-data/iowa/statewide/december-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

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