The segment of the highway between Denver and Salt Lake City is a scenic route providing access to several ski resorts and to recreational areas such as Rocky Mountain National Park and Dinosaur National Monument.
West of Denver, the route follows I-70 into the mountains before separating at Exit 233. This portion of the Interstate contains several miles of steep grades with a lot of truck traffic.
The 24-mile stretch of highway travelling west and north between the Interstate and the city of Winter Park passes through Arapaho National Forest. The highway winds its way through several switchbacks to cross the Continental Divide at Berthoud Pass (elevation 11,315 feet). Continuing on north and west of the pass, the route passes the resorts of Winter Park and Silvercreek.
From a junction west of Granby, US 34 travels north and east through Rocky Mountain National Park to Estes Park. This side route also passes by Lake Granby and the headwaters of the Colorado River.
Continuing west, US 40 parallels the Colorado River as far as the town of Kremmling (about 27 miles), while passing through narrow Bryers Canyon west of the town of Hot Sulphur Springs. From Kremmling the route turns to the northwest for about 27 miles.
At this point, the route crosses the Continental Divide twice as it goes through Muddy Pass (elevation 8,772 feet) and Rabbit Ears Pass (elevation 9,426 feet). It then passes through Routt National Forest, dropping in elevation as it enters the valley of the Yampa River.
Travelling the route in early to middle October provides a scenic view of the golden autumn leaves of the many cottonwood trees along the river banks and snow-capped peaks along the front range of the Rockies in Colorado and possibly the Wasatch Range in Utah. During winter months tire chains may be required.