I-70 Mountain Corridor

I-70 Mountain Corridor graphic with photo of traffic on the roadway

About the Corridor

The I-70 Mountain Corridor in Colorado spans from the Denver metro area in the east to Glenwood Springs in the west, cutting through the heart of the Rocky Mountains. This stretch of I-70 is a vital transportation route and a gateway to Colorado's ski resorts, outdoor recreation, mountain communities and more.

The corridor’s origins trace back to the Federal Highway Act of 1944, which authorized I-70 from Denver eastward to the Kansas state line. Initially, no mileage was allocated west of Denver. That changed with the 1956 Federal-Aid Highway Act, which expanded the national interstate system. Although Utah initially opposed a western extension due to the high costs and engineering challenges of building through mountainous terrain, the Colorado Department of Highways remained committed to pushing west. After negotiations, Utah agreed to the connection, and in October 1956, Congress approved the extension of I-70 from Denver to south-central Utah.

Westbound I-70 view from Exit 259Today, I-70 remains the only east-west interstate crossing Colorado. It connects major urban centers with rural communities and key tourist destinations, including Vail, Breckenridge, and Glenwood Springs. The corridor supports everything from freight transport and daily commuting to year-round tourism.

CDOT continues to invest in the I-70 Mountain Corridor — enhancing traffic flow, improving safety, expanding travel options, and preserving the corridor’s natural beauty and cultural heritage.