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Colorado Thanksgiving Travel: Even Treated I-70 Can Freeze
Denver, CO – Colorado drivers preparing for Thanksgiving travel on Interstate 70 should know that even a freshly treated mountain highway can remain dangerously icy. From the Denver metropolitan area
By Paige Sullivan · 2026-11-11T19:31:55.585Z
Denver, CO – Colorado drivers preparing for Thanksgiving travel on Interstate 70 should know that even a freshly treated mountain highway can remain dangerously icy. From the Denver metropolitan area to the Eisenhower Johnson Memorial Tunnels and Vail Pass, freezing pavement, snowfall and rapidly changing mountain weather can create hazardous conditions despite winter maintenance efforts.
According to winter maintenance guidance from transportation agencies, conventional road salt becomes less effective as pavement temperatures approach 20 degrees Fahrenheit. Its ice melting ability declines further in the teens and single digits, although performance varies with the material used and road conditions.
Why Treated Colorado Highways Can Still Freeze Salt and other deicing materials help prevent or remove ice, but they cannot guarantee traction.
Colorado's mountain highways present additional challenges. Pavement temperatures can vary sharply with elevation, while snow, wind and shade can cause icy patches to persist or return after treatment.
Along I 70, travelers encounter higher elevation terrain near the Eisenhower Johnson Memorial Tunnels in Summit County and Vail Pass between Summit and Eagle counties.
Drivers traveling from Denver through Idaho Springs in Clear Creek County, Silverthorne in Summit County and Vail in Eagle County may encounter substantially different road conditions along the same route.
I 25 through Colorado Springs, Denver and Fort Collins can also become hazardous during winter storms.
Thanksgiving Travel Raises the Stakes Thanksgiving falls Thursday, Nov. 26, bringing holiday traffic to Colorado's mountain corridors and Front Range highways.
If snow, freezing precipitation or rapidly falling temperatures develop during the holiday travel period, treated pavement could remain slippery.
Blowing snow, shaded curves and refreezing moisture can add to the danger, particularly at higher elevations.
Colorado also has traction and chain requirements that may apply to vehicles traveling affected mountain routes.
The Colorado Department of Transportation uses winter maintenance treatments, snowplows and traffic management measures, but none guarantees ice free travel.
Before departing, motorists should check National Weather Service forecasts and COtrip.org for current road conditions, closures, traction requirements and traffic cameras.
The bottom line: Treated does not mean safe. Reduce speed, increase following distances and be prepared for rapidly changing conditions, especially when crossing Colorado's mountain passes.