Interstate 25 - Colorado


View of the Colorado Springs skyline to the east of Interstate 25 at Colorado Avenue. Photo taken 11/11/03.

Routing

Interstate 25 is the main north-south freeway corridor through Colorado. Part of the Camino Real High Priority Corridor, Interstate 25 connects Mexico with Canada via ports at El Paso and a connection with Interstates 15 and 90 to Canada. The freeway underwent several improvements as part of this corridor strategy, including the massive T-REX improvement project in Denver, upgrades through Colorado Springs, and ongoing expansion of the freeway to six lanes along the Front Range.

Once completed in Colorado, Interstate 25 replaced U.S. 87. Officially the US highway is not inventoried in Colorado, as CDOT attributes all mileage along the implied concurrency to I-25.

Interstate 25 Colorado Highway Guides

History

Interstate 25 was the first mainline Interstate highway to be completed in Colorado. It was also the first segment of freeway to be built in Colorado. Known as the Valley Highway (U.S. 87), the first two-mile section of future Interstate 25 began construction in August 1948, and was completed in 1950. By 1958, the Valley Highway through the Denver metropolitan area was completed, only two years after the Interstate Highway Act was signed by President Eisenhower.

Early 1960s map showing the course of Interstate 25 (Valley Highway) north from the Mousetrap Interchange (junction with I-70) in Denver to Thornton.

Another pre-Interstate section of Interstate 25 that was grandfathered into the system included a 9.2-mile segment of freeway in Pueblo. Coonstruction there began in 1949 and was completed in 1958.

A notable milestone in the construction process was the extension of Interstate 25 into Wyoming on October 11, 1964. This date marked the first occasion when a Colorado Interstate actually crossed state lines and entered another state. A 26-mile segment of Interstate 25 heading north from Wellington opened at that time.

Segment Location Mileage (Approximate) Completion
Trinidad/Raton Pass From Raton Pass at New Mexico Line north to south edge of Trinidad 13 miles 1966
Trinidad Elevated portion, approximately three miles in length 3 miles 1963
Trinidad to Walsenburg From Trinidad north to Walsenburg. This was the last segment of I-25 to be completed in Colorado; it was dedicated on 9/21/69 21 miles 1969
Walsenburg Constructed as the Walsenburg Bypass 3 miles 1964
Walsenburg to Colorado City Connects north end of Walsenburg bypass with Colorado 165 interchange 22 miles 1968
Colorado City From Colorado 165 interchange in Colorado City north to Pueblo Boulevard 20 miles 1965
Pueblo Original urban freeway segment of Interstate 25 near downtown Pueblo ; includes 0.6-mile long bridge over Arkansas River 9.2 miles July 1959
South of Pueblo to Monument From south of Pueblo to north of Colorado Springs; connected pre-existing segments in Pueblo and Colorado Springs 67 miles 1961
Colorado Springs Original urban freeway segment of Interstate 25 near downtown Colorado Springs 12 miles July 1960
Monument Hill Monument to Larkspur 12 miles 1965
Larkspur to Castle Rock 9 miles 1968
Castle Rock to Denver Connects Castle Rock with Valley Highway in Denver 25 miles 1963
Denver From Evans Avenue north to 48th Avenue. This urban freeway was first section of Interstate 25 built; it was known as the Valley Highway (U.S. 87) 11.2 miles November 1958
Denver Northside From the north end of the Valley Highway (at 48th Avenue) north to 58th Avenue 0.5 mile 1961
Denver north From 58th Avenue to Colorado 7 14 miles 1963
Longmont Area From Colorado 7 to Colorado 66 14 miles 1961
North of Denver From Colorado 66 to U.S. 34 14 miles 1963
Fort Collins Area U.S. 34 to Harmony Road (former Colorado 68) 8 miles 1965
Colorado 68 to North of Wellington Harmony Road in Fort Collins to Buckeye Road (at that time, Interstate 25 became continuous from Walsenburg north to Colorado/Wyoming border) 23 miles 1968
North Link From north of Wellington (Buckeye Road) to Colorado-Wyoming Border 17 miles October 1964

Interstate 25 scenes
Lincoln Avenue westbound at Interstate 25 in Lone Tree, south of Denver. Photo taken 08/27/04.
Drivers depart from Lincoln Avenue east for Interstate 25 south. The freeway southbound sees one additional exit within the city of Lone Tree. Photo taken 11/10/03.
A loop ramp connects Lincoln Avenue eastbound with Interstate 25 north to Centennial, Greenwood Village and Denver. This sign was replaced by 2015, with expansion of the ramp to two lanes. Photo taken 11/10/03.

Page Updated April 14, 2017.

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