Interstate 70 History

The History of I-70 in Colorado

The Federal Highway Act of 1944 initially authorized Interstate 70 between Denver and the Kansas state line. As part of this act, there was no interstate mileage allotted west from Denver but this omission would be dealt with under the 1956 Interstate Act.

Initially, Colorado would not be able to build I-70 west of Denver since the state of Utah was not interested in a connecting interstate route through eastern Utah since the route it would follow – U.S. 6 & 50 – had mountainous terrain, which would mean it would be very costly to build an interstate route. However, officials with the Colorado Department of Highways were determined to have I-70 continue west of Denver . After much negotiation with Utah officials, Utah approved such a route and Congress approved the additional mileage of I-70 from Denver west to U.S. 91 (to become I-15) in south-central Utah in October, 1956.

I-70 Construction Timeline 

The 449.5 miles of I-70 were built in the following phases across Colorado, east to west:

  • Between Kansas state line and Burlington (14 miles) Construction Began: 1967 Construction Completed: 1969 Contractor: Schmidt Construction Company Cost: $3.3 million Resident Engineer: W.A. Woodson – Burlington
  • Between Burlington and Bethune (8 miles) Construction Completed: 1967
  • Between Bethune and Seibert (25 miles) Construction Completed - two lanes with interchanges: 1966 Construction Began: 1969 Construction Completed – four lanes: 1971 Contractor: Platte Valley Construction Company Cost: $1,967,410 Resident Engineer: W.A. Woodson – Burlington
  • Between Seibert and Flagler (10 miles) Construction Completed: 1974
  • Between Flagler and east of Genoa (24 miles) Construction Completed: 1975
  • Between east of Genoa and west of Genoa (4 miles) Construction Completed: 1975 Contractor: Abott and Sterling Paving Cost: $3 million Resident Engineer: Wayne Nesbitt
  • Between west Genoa and east of Limon (4.2 miles) Construction Completed: 1975 Contractor: Leone Construction Company Cost: $3 million Resident Engineer: Wayne Nesbitt
  • East Limon Bypass (3.8 miles) Construction Completed: 1975 Contractor: Goodell Brothers Cost: $3.5 million Resident Engineer: Wayne Nesbitt
  • West Limon Bypass (3.5 miles) Construction Completed: 1975 Contractor: Schmidt Construction Company Cost: $3.2 million Resident Engineer: Wayne Nesbitt
  • Between west of Limon and Agate (19 miles) Construction Completed – two lanes with interchanges: 1963/four lanes: 1968
  • Between Agate and Deer Trail (12 miles) Construction Completed: 1968
  • Between Deer Trail and Byers (12 miles) Construction Completed: 1967
  • Between Byers and Bennett (12 miles) Construction Completed: 1964
  • Between Bennett and Watkins (9 miles) Construction Completed: 1963
  • Between Watkins and East Colfax Avenue in Denver area (7 miles) Construction Completed: 1977
  • Between East Colfax Avenue and Peoria Street (7 miles) Construction Completed: 1966
  • Between Peoria Street and Colorado Boulevard (5 miles) Construction Completed: 1965
  • Between Colorado Boulevard and Interstate 25 Junction The first segment of I-70 to be built in Denver was through the northeast section of the city, along the route of 46 th Avenue . Construction of the 2.6 mile segment between Jackson Street (just west of Colorado Boulevard ) and the junction of I-25 started in 1961. The six-lane I-70 Viaduct was completed on September 12, 1964 for $12.5 million.
  • Prime Contractors
    • Leon K. Suhm, Incorporated
    • A.S. Horner
    • Ramsour Brothers
    • Peter Kiewit Sons' Company
  • Point of Interest
    • Originally built in 1951 as an interchange at 46th Avenue with what would become I-25, the interchange was nicknamed “The Mousetrap” in the late 1960s. It was dubbed by an airborne traffic reporter who described the connecting interstates as a maze that could trap a mouse. It currently serves an average of 416,000 vehicles daily, making it the busiest interchange in Colorado . In 1984, a truck carrying six Navy torpedoes overturned in the Mousetrap, closing both highways for hours and causing a large-scale evacuation of nearby neighborhoods. That served as the impetus for its reconstruction, beginning in 1987 and completed in 2003.
  • Between Interstate 25 Junction and Sheridan Boulevard Construction on the second segment began on October 21, 1964, along a route that generally followed West 48 th Avenue through northwest Denver . Work on the segment between I-25 and Federal Boulevard was completed on December 10, 1965.
  • Construction between Federal Boulevard and Sheridan Boulevard began on November 27, 1964. It was opened to traffic on July 9, 1966. Cost: $4,501,000
  • Prime Contractors
    • Peter Kiewit Sons' Company
    • Northwestern Engineering Company
    • Thomasson Concrete Company
    • A. Keesen and Sons
    • Resident Engineer: Robert W. Linke
  • Point of Interest: The major challenge of this segment involved threading an interstate highway past Rocky Mountain Park, past Rocky Mountain Lake, Berkeley Lake, Lake Rhoda (Lakeside Amusement Park) and between Berkeley Park and Willis Case Golf Course. It entailed deepening Berkeley and Rocky Mountain Lakes , to keep their water capacity unchanged by compensating for a minimal loss of surface area. What emerged was a gently winding and beautifully landscaped section of I-70.
  • Between Sheridan Boulevard and Wadsworth Boulevard (2 miles) Construction Completed: 1967
  • Between Wadsworth Boulevard and Kipling Street (2 miles) Construction Completed: 1968
  • Between Kipling Street and Ward Road (1.7 miles) Construction Began: 1967 Construction Completed: 1968
  • Between Ward Road and West Colfax Avenue - U.S. 40 (4 miles) Construction Completed: 1970
  • Between West Colfax Avenue and State Highway 26/U.S. 40 Junction – entrance to Mount Vernon Canyon (2.9 miles) Construction Began: 1967 Construction Completed: 1969 Cost: $4,728,558
  • Prime Contractor:
    • Colorado Constructors, Inc.
    • A.S. Horner Construction Company, Inc.
    • Peter Kiewit Sons' Company
  • Point of Interest: This section of I-70 slices through a prominent terrain feature called the Hogback. It was formed 50 to 80 million years ago with the gigantic upheaval that produced the Rocky Mountains . The Hogback is not simply layers of nondescript rock, tipped on end. The strata stand out in beautiful, well-defined pastel bands. The site now is a nature study area complete with marked trails to points of special interest.
  • Between State Highway 26 and Lookout Mountain Exit – Mount Vernon Canyon (2.8 miles) Construction Began: Construction Completed: 1970 Cost: $2.3 million
  • PRIME CONTRACTORS:
  • Schimkat Construction Company
  • Asphalt Paving Company
  • Resident Engineer: Russel A. Glad
  • Point of Interest: Runaway Truck Ramps are part of the landscape along some of I-70's steeper downhill grades. These ramps are designed to stop trucks from going out of control when they experience brake failure or due to other circumstance. After a number of truck accidents and runaway trucks on the steeper highway grades in the 1970's, CDOT decided to build the ramps at key mountain highway locations. Five ramps are in service along the I-70 corridor: one on eastbound I-70 in Mount Vernon Canyon , two on westbound I-70, west of the Eisenhower Tunnel, and two on westbound I-70, west of Vail Pass.
  • Between Lookout Mountain Exit and Genesee Mountain (2.4 miles) Construction Completed: 1970 Cost: $2.1 million
  • Prime Contractor:
    • H-E Lowdermilk Company
    • Resident Engineer: R. J. Brasher
  • Between Genesee Mountain and El Rancho Exit (2 miles) Construction Completed: 1972
  • Between El Rancho Exit ( Evergreen Parkway ) and Beaver Brook (4.0 miles) Construction Began: 1970 Construction Completed: 1972
  • Between Beaver Brook and Junction U.S. 6 (4 miles) Construction Completed: 1975
  • Between Junction U.S. 6 and east Idaho Springs (3 miles) Construction Completed: 1961
  • Between east & west Idaho Springs – Idaho Springs Bypass (2 miles) Construction Completed: 1961
  • Between west Idaho Springs and Junction U.S. 40 – Empire (7 miles) Construction Completed: 1966
  • Between Junction U.S. 40 and Silver Plume (6 miles) Construction Completed: 1968
  • Between Silver Plume and Eisenhower Tunnel (10 miles) Construction Completed: 1972