Short answer: Idaho’s final 2025 report does not name one cause for every crash. For one-vehicle crashes, its top recorded factors were animals in the road, speed, and failing to stay in a lane. For crashes with more than one road user, the top factors were failing to yield, following too closely, and inattention or distraction. These are factors marked by officers, not court findings about fault.
What Does ITD Mean by a Contributing Circumstance?
The Idaho Transportation Department’s 2025 Statewide Crash Database report comes from reports filed by Idaho law enforcement. For each vehicle, an officer may mark as many as three factors that may have played a part. One crash may therefore appear in more than one group.
An officer’s label is not a court finding of negligence, legal cause, or each person’s share of fault. ITD also keeps crash facts, vehicle facts, and outcomes for people at different data levels. Mixing those levels can turn a useful number into a misleading claim.
Single-Vehicle Crashes: Animals, Speed, and Lane Departure Led the Figure
ITD counted 7,954 one-vehicle crashes in 2025. They were 7,954 / 28,127 x 100 = 28.28% of all reported crashes. They accounted for 107 / 231 x 100 = 46.32% of fatal crashes. Crashes with more than one road user were more common. Still, one-vehicle crashes made up a larger share of fatal crashes than of all crashes.
| Order in figure | Recorded circumstance | ITD published percentage | Raw numerator / numeric denominator |
|---|---|---|---|
| 1 | Animal(s) in roadway | 23% | Not published in the annual report |
| 2 | Speed | 18% | Not published in the annual report |
| 3 | Failed to maintain lane | 15% | Not published in the annual report |
| Tied next | Inattention or distraction | 9% | Not published in the annual report |
| Tied next | Alcohol or drug impaired | 9% | Not published in the annual report |
ITD excluded “none,” “not applicable,” and “unknown” from its percentage work. It grouped smaller factors as “all other.” The report does not give the count behind each slice or the base count used for Figure 3. We therefore repeat ITD’s rounded labels. We do not present them as our own rates.
Multiple-Vehicle Crashes: Yielding and Following Distance Led
ITD counted 20,173 crashes with more than one road user in 2025. That is 20,173 / 28,127 x 100 = 71.72% of all crashes. In this section, ITD includes crashes between motor vehicles. It also includes cases in which a motor vehicle strikes a person walking, a bicyclist, a train, or an equestrian.
| Order in figure | Recorded circumstance | ITD published percentage | Raw numerator / numeric denominator |
|---|---|---|---|
| 1 | Failed to yield | 20% | Not published in the annual report |
| 2 | Followed too closely | 18% | Not published in the annual report |
| 3 | Inattention or distraction | 15% | Not published in the annual report |
| 4 | Failed to obey signal or stop sign | 7% | Not published in the annual report |
| 5 | Improper lane change | 6% | Not published in the annual report |
| Tied next | Failed to maintain lane | 4% | Not published in the annual report |
| Tied next | Improper turn | 4% | Not published in the annual report |
| Tied next | Speed | 4% | Not published in the annual report |
Figure 4 also omits the raw count and base count behind each percentage. It does not show factors below 2% one by one. The figure supports the order above and a broad view of the pattern. It does not support a more precise ranking built from the report alone.
There Is No Single ITD “Number One Cause of Death”
ITD uses different measures for different questions. In fatal one-vehicle crashes, “overturn” was the top most harmful event in Table 7. ITD lists it at 52.3% of vehicles. That label means the event that caused the most injury or property damage to a vehicle. It does not explain why the vehicle rolled, name a medical cause of death, or decide legal fault.
For all fatal crashes, ITD Figure 12 shows alcohol or drug involvement at 21%, failure to maintain lane at 17%, and speed at 15%. The report does not give the raw counts for those bars. An officer may also mark up to three factors for each vehicle. The percentages cannot be added or treated as separate shares of fatal crashes.
Aggressive, Distracted, and Impaired Driving Are Overlapping Focus Categories
ITD also reports broad highway-safety groups. They overlap with the factors above and may overlap with each other. Do not add their shares.
| ITD category | Crash calculation | Share of all crashes | Fatality calculation | Share of all fatalities |
|---|---|---|---|---|
| Aggressive driving | 13,610 / 28,127 | 48.39% (ITD rounds to 48%) | 99 / 252 | 39.29% |
| Distracted driving | 4,396 / 28,127 | 15.63% (ITD: 15.6%) | 34 / 252 | 13.49% (ITD: 13.5%) |
| Impaired driving | 1,613 / 28,127 | 5.73% (ITD: 5.7%) | 87 / 252 | 34.52% (ITD: 34.5%) |
ITD’s aggressive-driving group includes failure to yield, running a stop sign or signal, speeding, driving too fast for conditions, and following too closely. A crash enters the distracted-driving group when an officer marks inattention or a distraction in or on the vehicle. The impaired-driving group comes from the crash report. It can include an impaired driver, pedestrian, or bicyclist.
Youth, Restraint Use, and Economic Cost Use Different Denominators
ITD also tracks youthful-driver involvement, safety-restraint use, and modeled economic cost. These measures provide safety context, but they are not additional causal rankings. Each uses a different population or method, so their percentages cannot be compared as if they shared one denominator.
| Measure | 2025 value | Numerator, denominator, and calculation | Definition or limit |
|---|---|---|---|
| Crashes involving a driver age 15-19 | 6,092; 21.66% of all crashes | 6,092 / 28,127 x 100 = 21.6589% | Crash involvement, not a finding that the youthful driver caused the crash; ITD Table 36 |
| Drivers age 15-19 as a share of licensed drivers | 87,172; 5.83% | 87,172 / 1,495,112 x 100 = 5.8305% | Licensed-driver distribution; ITD Tables 17 and 36 |
| Drivers age 15-19 in fatal or injury crashes | 1,876; 12.43% | 1,876 / 15,093 x 100 = 12.4296% | Drivers, not crashes or people injured; 1,876 is the sum of the age 15-19 rows in ITD Table 17 |
| Fatal-or-injury crash involvement ratio for drivers age 15-19 | 2.13; ITD reports 2.1 | 12.4296% / 5.8305% = 2.1318 | Share of drivers in fatal or injury crashes divided by share of licensed drivers; not an individual probability |
| Observed statewide seat-belt use | 87.0% | Raw people observed / eligible people observed is not published in the annual report | Representative shoulder-harness observation at 180 sites for passenger cars, pickups, SUVs, and vans; ITD Table 27 and release |
| Belt use among killed passenger-vehicle occupants age 7 and older | 70 of 169; 41.42% | 70 / 169 x 100 = 41.4201% | Crash-reported group: 70 used a belt, 71 did not, and 28 were unknown; ITD Tables 29-30 |
| Modeled economic cost of all Idaho crashes | $6,081,450,113; $2,996 per resident | $6,081,450,113 / 2,029,700 residents = $2,996.23, reported as $2,996 | AIS-to-KABCO and U.S. DOT value-based estimate, not bills, compensation, or case value; ITD Table 4 |
| Modeled economic cost of impaired-driving crashes | $1,534,004,472; 25.22% of statewide estimate | $1,534,004,472 / $6,081,450,113 x 100 = 25.2243% | ITD Table 22 estimate; the report rounds the share to 25% |
| Modeled economic cost of crashes involving youthful drivers | Nearly $954 million; ITD reports 16% | Comparison denominator is the $6,081,450,113 statewide estimate; exact youthful-driver dollars are not published | Published approximate amount and rounded share in the Table 36 narrative; do not reverse-engineer false precision |
Youthful-driver involvement is not a causation finding
ITD defines youthful drivers as ages 15 through 19. The 2.1 figure is an involvement ratio: that group was 5.8% of licensed drivers but 12.4% of drivers in fatal or injury crashes. It is not adjusted for miles driven and does not say that every youthful driver caused the crash. The 32 people killed in crashes involving youthful drivers in 2025 were people of all ages; ITD reports that 17 were the youthful drivers.
Observed belt use and crash-reported belt use are different samples
The 87.0% observed-use figure comes from a representative roadside survey at 180 sites, according to ITD’s release, not from all Idaho occupants or the crash database. The annual report does not publish the number of people observed, so that percentage cannot be independently recomputed from the report. The 70-of-169 figure concerns only killed occupants age 7 and older in specified passenger vehicles. It includes a separate unknown-use group. Neither percentage should be substituted for the other.
Economic cost is a model, not a legal recovery measure
ITD applies injury-severity occurrence costs derived from an AIS-to-KABCO conversion resource and U.S. Department of Transportation valuation guidance. The result estimates economic impact for traffic-safety analysis. It is not a sum of medical bills, verdicts, settlements, or damages available in any claim. Focus groups can overlap, so their modeled costs must not be added together.
What These Patterns Suggest for Prevention
The data supports practical steps. It does not prove that one act caused a given crash:
- Scan for wildlife and roadway hazards, especially when visibility is limited.
- Choose a speed that is lawful and appropriate for traffic, visibility, weather, and road conditions.
- Leave enough following distance to respond without abrupt braking.
- Approach intersections ready to yield and obey traffic controls.
- Put distracting tasks away before driving and arrange a sober ride whenever alcohol or impairing drugs are involved.
These steps address common patterns. They cannot guarantee that a crash will not occur.
Statewide Patterns Do Not Determine Fault in One Crash
A statewide group does not prove who was at fault in one crash. That review may use the crash report, photos, video, witness accounts, road evidence, vehicle data, and other records. Read how fault is determined in Idaho car accidents, what evidence may matter in an Idaho injury case, and how Idaho comparative-fault rules work.
For statewide totals and five-year rates, use the separate Idaho car-accident statistics reference. If you want the firm to review the facts of one crash, visit the Idaho car-accident practice page.
Methodology, Limitations, and Update Schedule
- Dataset: ITD Statewide Crash Database, calendar year 2025.
- Publication: Idaho Traffic Crashes 2025, released August 13, 2026.
- Coverage: qualifying motor-vehicle crashes on public roads investigated by law enforcement.
- Counting rule: crash-, unit-, and person-level measures use different denominators; an officer may record up to three contributing circumstances per vehicle.
- Figure limitation: Figures 3, 4, and 12 and Table 7 publish rounded percentages without the raw category counts needed for independent calculation. Those values are labeled as published, not recomputed.
- Recomputed values: Focus-category shares use the published category count divided by 28,127 total crashes; fatality shares use the category’s people killed divided by 252 total fatalities.
- Youthful-driver calculations: Table 17 age rows supply the numeric licensed-driver and fatal-or-injury-driver denominators; Table 36 supplies crash and fatality context. Involvement is not assigned causation.
- Restraint measures: Table 27’s observational result and Tables 29-30’s crash-reported result use different groups. The report does not publish the raw statewide observational count.
- Economic-cost method: Table 4 and Table 22 are modeled estimates based on injury-severity occurrence values. They are not case damages, and overlapping focus-area estimates are not additive.
- Companion files: A contributing-circumstance table and a separate youth/restraint/economic context table record each value, formula, locator, and source limitation for CMS upload.
- Review owner: Annual data verification for this page belongs to Attorneys of Idaho content operations.
- Next source check: Begin on August 2, 2027 and inspect ITD’s annual-report library each week until the final 2026 edition appears. Complete the corresponding page and data-file revision within 10 business days after publication.
Download the Attorneys of Idaho companion files: Idaho 2025 contributing-circumstances companion CSV and Idaho 2025 youth, restraint, and economic-context companion CSV. These Attorneys of Idaho research companions organize information from the cited sources; they are not official ITD datasets or raw crash records.
Sources and References
- Idaho Transportation Department, Idaho Traffic Crashes 2025 – explanation of data; Tables 4, 6-7, 14, 17, 21-22, 27, 29-30, 33, 35-36; and Figures 3-4 and 12.
- Idaho Office of Highway Safety’s crash-data and annual-publication hub – current report library and methodology entry point.
- ITD’s August 13, 2026 release for the final 2025 report – publication date, 180-site restraint-survey context, and agency summary.
This article provides general information, not legal advice. A statistical category does not establish fault, causation, damages, or the outcome of a particular matter.
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Reviewed by J.W. Bond , Founding Attorney and Partner on September 2, 2026.