MileCheckWhich highways are most dangerous in winter?
There is no official list. NHTSA records the weather and road surface for every fatal crash, but it publishes no ranking by highway. What exists is one national average and a handful of state DOT closure records. This page lists what those records support and says where each number comes from.
Is there a national ranking of winter crashes by highway?
No. The Fatality Analysis Reporting System (FARS) codes snow, sleet and icy pavement for each fatal crash, and FHWA publishes the national totals from it. Neither agency publishes a winter table by route. The numbers below are the national picture, averaged over 2019 to 2023.
| Each year, on average | Count | Share |
|---|---|---|
| Crashes in adverse atmospheric weather (rain, snow, sleet, fog, wind) | 744,911 | 12% of all crashes |
| People killed in those crashes | 3,807 | 9% of crash deaths |
| Crashes in snow, sleet, hail or freezing rain | 219,942 | see note |
| People killed in snow, sleet, hail or freezing rain | 407 | 11% of weather-related deaths |
Source: FHWA Road Weather Management Program, five-year averages 2019 to 2023 from NHTSA data. (FHWA) Note: FHWA's page gives the freezing-precipitation row as 18 percent of weather-related crashes, but 219,942 is about 30 percent of 744,911. We show the counts and leave that percentage out. FHWA counts weather by what was in the air, not by the road surface.
A NOAA National Severe Storms Laboratory study used a wider definition. It counted every October to April fatality with ice, snow or slush on the road, or snow, sleet or freezing precipitation in the air. That came to 11,966 deaths from 2008 to 2019, about 1,000 a year. Among the 5,317 fatalities the study could match to a nearby weather station, 46 percent happened in snow alone, and only one-third had a National Weather Service winter weather watch, warning or advisory in effect. (Tobin et al., Weather, Climate, and Society, 2022) The study maps deaths by climate region, not by highway. The Central, East North Central and Northeast regions held the most.
Which passes and corridors have the worst closure record?
Only a few DOTs publish closure counts, and each counts something different. Colorado counts closures and hours on one corridor. Wyoming publishes a yearly closure table per interstate. Caltrans counted closures and chain-control hours for one winter. Utah posted hours for one canyon. Each row stands on its own record. The rows are not comparable across states, and they are not a ranking of crash risk.
| Road | What the DOT published | Our pages |
|---|---|---|
| I-70 mountain corridor, Colorado Glenwood Springs to Georgetown |
More than 200 closures in winter 2024-25 through March 21, 2025, up 40 percent on 2023-24 (CDOT data, reported by the Colorado Sun). 99 full closures in 2024, 161 hours closed (Vail Town Council letter to the governor). 900 to 1,000 crashes a year on the corridor, about 15 percent with a commercial vehicle (Colorado State Patrol). (Colorado Sun, March 21, 2025) CDOT's own count for October to December 2019: 124 crashes, more than 114 hours of lane closure, 114 safety closures. (CDOT, Feb. 13, 2020) | Vail Pass · Eisenhower Tunnel · I-70 corridor · Why I-70 closes · CDOT plow positions |
| SR-210, Little Cottonwood Canyon, Utah | 34 full-canyon closures and 1,480 hours closed in winter 2022-23 (UDOT figures posted May 2023, reported by SnowBrains). (SnowBrains, May 24, 2023) Alta counted 98 avalanches that reached the highway that season. (Alta) That is one winter, not an average. | Little Cottonwood Canyon · Utah cameras and plows · UDOT plow positions |
| I-80, Wyoming | An average of 50 a winter from 2016-17 to 2020-21, from a low of 34 to a high of 67. WYDOT's table is titled yearly road closure days and labels the average as closures per year, so read the figure as WYDOT's own count, not an exact day count. WYDOT counts October 1 to May 31. (WYDOT, Yearly Road Closure Days) | Why I-80 closes · I-80 corridor · Wyoming road conditions |
| I-80, Donner Pass, California | 15 closures, 78 days with chain controls, about 900 hours of chain control and 730 inches of snow in winter 2022-23 (Caltrans District 3 season recap, reported by Active NorCal). (Active NorCal, May 20, 2023) Caltrans publishes no multi-year table, so there is nothing to compare it with. | Donner Pass · R1, R2 and R3 · California chain law |
| I-25, Wyoming | An average of 15 a winter on the same WYDOT table, 2016-17 to 2020-21, high of 23. (WYDOT) | Wyoming road conditions |
| I-90, Wyoming | An average of 10 a winter on the same WYDOT table, 2016-17 to 2020-21, high of 18. (WYDOT) | I-90 corridor |
| I-90, Snoqualmie Pass, Washington | WSDOT publishes no season total. Each avalanche-control closure holds traffic 30 minutes to two hours, longer in a big storm. About 28,000 vehicles a day cross the pass, 5,600 of them freight. (WSDOT) | Snoqualmie Pass · Why it closes · Washington chain law |
| US-2, Stevens Pass, Washington | In January 2025 WSDOT said only three Stevens Pass closures in the preceding five years were caused by weather itself. The rest came from crashes, trucks that did not chain up, and avalanche control. (WSDOT blog, Jan. 30, 2025) | Stevens Pass |
Three of the records above reached us through a UDOT social post, a town council letter and a news site's copy of a Caltrans recap rather than a published report, and each source line says so. We left out roads with no published count, among them I-84 over Cabbage Hill in Oregon, I-90 over Lookout Pass and US-2 over Marias Pass in Montana. We found no published count for any of them.
What does the closure data have in common?
Three causes show up in the records. WSDOT says crashes and trucks that did not chain up cause most Stevens Pass closures, and CDOT's I-70 figures count crashes and spun-out vehicles rather than snow depth. (WSDOT) On I-80 in Wyoming, WYDOT names limited visibility, drifting snow and a crash blocking all lanes as its three closure reasons, and the first two are wind. Why does I-80 close so often in Wyoming? has the detail. And avalanche control closes the mountain roads on purpose, on the agency's schedule, which is why Little Cottonwood Canyon and Snoqualmie Pass post planned closures before a storm.
What does MileCheck's own data show?
Our monthly road report counts every DOT event we log, from one incident snapshot per state per day, with duplicates removed by incident id. In September 2026, before snow, I-80 carried 671 events across 11 states, 7 of them in Wyoming. I-70 carried 471, 297 of them in Colorado. I-90 carried 449, 53 in Washington. Most were construction. Winter counts, with closures separated out, go in the monthly road report as each month closes. We do not yet have a full winter in the archive, so there is no MileCheck ranking here.
How do I check one of these roads before I drive?
- Read the DOT's own pass report. It is the only place that says open or closed. Our guide how do you know if a mountain pass is open lists the official page for each state.
- Look at the camera, then the closure list. A camera shows snow and traffic. It does not say the road is open. Our pass pages show both.
- Check the plow map where it exists. Colorado, Utah and the other states on our snowplow map publish truck positions. A pin is where the truck is, not a sign that the road has been worked. Washington, Oregon and California do not publish positions.
Before you go, read how do you drive safely in winter conditions for chain law by state, following distance and what to carry.
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Questions, answered
Which highways are most dangerous in winter?
No agency ranks highways by winter crashes. NHTSA's FARS data gives national totals only. Among state DOT closure records, I-70 in Colorado had more than 200 closures in winter 2024-25, Little Cottonwood Canyon in Utah was closed 1,480 hours in 2022-23, I-80 in Wyoming averages 50 closures a winter on WYDOT's table, and Donner Pass closed 15 times in 2022-23.
How many people die in winter weather crashes each year?
FHWA's five-year average for 2019 to 2023 is 407 deaths a year in snow, sleet, hail or freezing rain (FHWA, from NHTSA data). A NOAA study that also counts icy, snowy or slushy pavement found about 1,000 a year from 2008 to 2019 (Tobin et al., 2022).
Does FARS rank highways by winter crashes?
No. FARS records weather and road surface for each fatal crash, and FHWA publishes national averages from it. Neither publishes a per-route winter ranking.
Which interstate closes most often in Wyoming?
I-80. WYDOT's yearly closure table averages 50 a winter for I-80 from 2016-17 to 2020-21, against 15 for I-25 and 10 for I-90.
How often does I-70 close in Colorado in winter?
CDOT data reported in March 2025 showed more than 200 closures between Glenwood Springs and Georgetown in winter 2024-25, a 40 percent rise on the winter before. A Vail Town Council letter counted 99 full closures and 161 closed hours in 2024.
Why are these numbers not comparable?
Each DOT counts something different. Colorado counts closures and hours on one corridor, Wyoming publishes a yearly closure table, Caltrans and UDOT published one winter each. The page lists each record on its own terms and says so.
Sources read October 15, 2026. FHWA, NHTSA and NOAA figures are multi-year averages. The state DOT counts are for the winters named and change every season, so check the live feed before you drive.