This Thanksgiving, I-70 was closed from the Denver suburbs to the Eastern boundary of Colorado due to visibility impairing snow storms. This is a common occurrance. It has already happened, at least, one other time this year, and it will likely happen again. I-70 through the mountains is also often closed for rockslides and snow.
Considering that I-70 is the main road connecting the East to the West across the continental divided, without deteuring far to the North or South, this is a big deal. If the United States government ever grows truly disfunctional, I-70 in Colorado will probably be one of the very first crucial links in our national highway system to fail.