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List of Interstate Highways in Colorado

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Interstate Highways of the Colorado State Highway System
Interstate 76 Business marker
Standard highway markers used in the state of Colorado for Interstate 70, Interstate 225, and Interstate 76 Business
Map
Interstate Highways highlighted in red
System information
Maintained by CDOT
Length956 mi[1] (1,539 km)
FormedOctober 11, 1964[1]
Highway names
InterstatesInterstate X (I-X)
Business routes:Interstate X Business (I-X Bus.)
System links
  • Colorado State Highway System

The Interstate Highways in Colorado are the segments of the national Dwight D. Eisenhower System of Interstate and Defense Highways that are owned and maintained by the state of Colorado, totaling about 956 miles (1,539 km).[1] Colorado has three main highways (two-digit routes), and two auxiliary highways (three-digit routes), totaling five Interstates, all are located within the Denver metropolitan area. The longest Interstate in Colorado is Interstate 70 (I-70), which is 449.58 miles (723.53 km)[2] There are also 17 active business routes and seven former business routes, most of them are from I-70. The last segment of Interstate Highway to open up to date was I-76, which was between Pecos Street and I-25 northwest of Denver.[1]

Description

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The Colorado Department of Transportation (CDOT) is the agency responsible for maintaining the Colorado State Highway System, which includes the Interstate Highways in Colorado.[3] These highways are built to Interstate Highway standards, which are freeways with speed limits up to 75 miles per hour in rural areas and 65 miles per hour in urban areas, primarily in the Denver and Colorado Springs areas. In very populated areas where the traffic volume is the greatest, the speed limit can drop as low as 55 miles per hour. The numbering scheme used to designate the Interstates was developed by AASHTO, an organization composed of the various state departments of transportation in the United States.[4]

The Interstate Highway System covers approximately 956 miles (1,539 km) in Colorado which consists of three primary highways and two auxiliary highways. There are also a total of 17 active business routes in the state, 13 of which are business routes of I-70. The longest highway in the state is Interstate 70 which has a span of 449.51 miles (723.42 km) that runs west to east across the state, serving Grand Junction, Denver, Aurora, and Limon. Interstate 270, I-70's only auxiliary route in Colorado, is the shortest interstate highway in the state, spanning about 7 miles (11 km). All of Colorado's interstates are located in the Denver–Aurora Metropolitan Area while other major cities in Colorado except Boulder and Greeley are only served by the same primary routes that run through the Denver Metro Area.

History

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1955 map showing planned Interstate highways around Denver

Colorado had already begun planning a modern inter-city route along the Front Range as early as 1944. The first section of freeway was also in 1944 which would later become Interstate 70 that originally terminated near I-25 in Denver before getting extended across the Rocky Mountains along the US 6 and US 40 corridors.[5] The cities of Denver and Pueblo began constructing a multi-lane route that would become Interstate 25. The first segment of freeway was a two mile segment in Denver, which began construction in August 1948 and was completed two years later. Then, the entire segment of the Valley Highway was completed in 1958, later receiving the Interstate 25 designation.[1] Pueblo would complete the section of freeway in 1959.[6] Interstate 76 is the last primary highway that was completed in 1993, then was later extended to Interstate 70 in Arvada which wasn't completed until 2002.[7] It originally started as Interstate 80S which had two segments in Denver and northeastern Colorado. In 1976, AASHTO renumbered the route to I-76 in accordance with its policy against suffixed routes to eliminate confusion with Interstate 80.[8]

Two more auxiliary routes were planned in the Denver Metro Area around the same time as the primary routes. Interstate 270 was the first route proposed near Denver. It originally was proposed by CDOT to be designated as Interstate 425 but it was rejected by AASHTO and was renumbered to I-270 on February 26, 1959, about six years before construction began between I-70 and Vasquez Boulevard. It was later extended to I-76 (I-80S) in 1967 and then to I-25 in 1999 to continue along the Denver–Boulder Turnpike.[9] A year prior to I-270 being constructed, Interstate 225 would also begin construction, starting at I-70 and would work its way south through Aurora and into the Denver Tech Center by 1976.[10] A full beltway around Denver was proposed by CDOT as well and was added to the Federal Highway Act of 1968 and was to be Interstate 470. The proposal was rejected by the Colorado Department of Health and then by Colorado Governor Richard Lamm suggesting alternatives to land uses that would be more environmentally friendly. It was later decided that the federal highway funds were to be used to construct a partial beltway in the southwest suburbs that was known as the Centennial Parkway and then receiving the State Highway 470 designation. The beltway was later extended east of I-25 and is now a toll road known as E-470 and then eventually west of I-25 north of Denver, known as Northwest Parkway. The 470 beltway remains as an incomplete beltway with the western portion between Broomfield and Golden missing.

Interstate highways

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Number Length (mi) Length (km) Southern or western terminus Northern or eastern terminus Formed Removed Notes
I-25 298.87[11] 480.98 I-25 at the New Mexico state line I-25 at the Wyoming state line 01958-01-011958[6] current Runs concurrent with US 87 in its entire length in the state. Nicknamed the Valley Highway through Denver, the Monument Valley Highway in Colorado Springs, and the John F. Kennedy Memorial Highway in Pueblo. It is also part of the unofficial Pan-American Highway[6]
I-70 449.589[12] 723.543 I-70 at the Utah state line I-70 at the Kansas state line 01956-01-011956[1] current Longest interstate in Colorado. It was the first interstate highway to be designated in the state of Colorado in 1956. A section from I-270 in Denver to the Kansas State Line is known as the Dwight D. Eisenhower Highway[13]
I-76 187.29[7] 301.41 I-70 in Arvada I-76 at the Nebraska state line 01976-01-011976[7] current Originally I-80S until 1976. Last interstate to be completed in the state of Colorado. Completed in 1993.[1]
I-80S 178.22[7] 286.82 I-25/US 87 in North Washington I-80S at the Nebraska state line 01958-01-011958[8] 01976-01-011976 Two sections of freeway located near Denver and in northeastern Colorado, near the Nebraska border. It was renumbered to I-76 by AASHTO to conform to policy against suffixed routes[8]
I-225 11.959[10] 19.246 I-25 in Denver I-70 in Aurora and Denver 01976-01-011976[10] current Only active Colorado interstate that doesn't run concurrent with another highway in its entire length. It is also the only auxiliary route for I-25 in general. Completed in 1976[10]
I-270 7.107[14] 11.438 I-25/US 36 in unincorporated Adams County I-70 in Denver 01965-01-011965[9] current Runs concurrent with US 36 in its entire length. Also known as the Dwight D. Eisenhower Highway[13]
I-425 5.35[15] 8.61 I-25/US 36 in unincorporated Adams County I-70 in Denver 01958-01-011958 01959-01-011959[15] Proposed designation for I-270 but was rejected and renumbered by AASHTO in 1959[15]
I-470 — — Beltway around Denver 01968-01-011968[16] — Proposed, but cancelled due to environmental concerns. Now SH 470 (known locally as C-470), E-470, and Northwest Parkway
  •       Former
  • Interstate Highways
  • a picture of I-25 in Denver
    I-25 during rush hour near Downtown Denver
  • I-25 between Colorado Springs and Denver
    I-25 between Colorado Springs and Denver
  • A highway about to curve to the right while descending down a canyon
    I-70 crossing the Rocky Mountains
  • Automobiles are driving on a road leading to one of two openings in a building against a mountain. Letters above each opening read "Johnson Tunnel 1979" and "Eisenhower Tunnel 1973". On the roof of the building, large ventilation hoods are visible.
    I-70 at the Eisenhower Tunnel
  • I-76 and its western terminus at I-70
    I-76 and its western terminus at I-70
  • I-76 in northeastern Colorado, near Brush
    I-76 in northeastern Colorado, near Brush
  • picture of a bus station near the highway
    I-225 with the Dayton RTD Station in the center near Aurora
  • A sign in a snowy area indicating an exit for I-270 to Fort Collins and SH 35 as the next exit
    I-270 exit along I-70

Business routes

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Number Length (mi) Length (km) Southern or western terminus Northern or eastern terminus Formed Removed Notes
I-25 BL 0.5 0.80 I-25/US 85/US 87/US 160 in Trinidad I-25/US 85/US 87/US 160 in Trinidad — 02009-01-012009 Eliminated by a reconstruction project in 2009 which removed the original northern terminus at I-25[17]
I-25 BS 1.948[18] 3.135 Main Street/S. Fir Street in Aguilar I-25/US 85/US 87/US 160 in Aguilar — — Inventoried as State Highway 25B[18]
I-25 BL 4.039[19] 6.500 I-25/US 85/US 87/US 160 in Walsenburg I-25/US 85/US 87 in Walsenburg — — Inventoried as State Highway 25C[19]
I-25 BL 6.75 10.86 I-25/US 24/US 85/US 87 in Colorado Springs I-25/US 85/US 87 in Colorado Springs — 02007-01-012007 Was signed along the CanAm Highway in downtown Colorado Springs. Also ran concurrent with US 85 in its whole length. Decommissioned in December 2007 as part of a highway swap to designate Powers Boulevard as SH 21
I-25 BL 1.2 1.9 I-25/US 85/US 87 in Castle Rock I-25/US 85/US 87 in Castle Rock — 01996-01-011996 Likely unsigned
I-70 BL 13.265[20] 21.348 I-70/US 6/US 50 in Grand Junction I-70/US 6 in Clifton — — Inventoried as State Highway 70B. Also inventoried as State Highway 70Z along Ute Avenue[20]
I-70 BL 3.7 6.0 I-70/US 6 in Palisade I-70/US 6 in Palisade — —
I-70 BL 4.0 6.4 I-70/US 6 in Rifle I-70/SH 13 in Rifle — 02004-01-012004
I-70 BS 0.222[21] 0.357 I-70 in Silt US 6 in Silt — — Unsigned. Inventoried as State Highway 70E[21]
I-70 BS 0.346[22] 0.557 I-70 in Eagle US 6 in Eagle — — Unsigned. Inventoried as State Highway 70F[22]
I-70 BS 0.577[23] 0.929 I-70 in Edwards US 6 in Edwards — — Unsigned. Inventoried as State Highway 70G[23]
I-70 BS 0.43 0.69 I-70 in Avon US 6 in Avon — 01999-01-011999
I-70 BL 2.3 3.7 I-70/US 6 in Frisco I-70/US 6/SH 9 in Frisco — —
I-70 BL 2.711[24] 4.363 I-70/US 6/US 40 in Idaho Springs I-70/US 6/US 40 in Idaho Springs — — Signed at both termini. Unsigned along Colorado Boulevard. West end inventoried as State Highway 70K and east end inventoried as State Highway 70R[24]
I-70 BL 26.80 43.13 I-70/US 40 in West Pleasant View I-70/US 36/US 40/US 287 in Aurora — — Runs concurrent with US 40 in its entire length. Also cosigned with US 287. Part of Colfax Avenue which serves Lakewood, Denver, and Aurora
I-70 BS 0.400[25] 0.644 I-70/US 36/US 40/US 287 in Watkins SH 36 in Watkins — — Only signed along I-70. Was accidentally indicated with multi-colored I-70 shield at exit on westbound I-70.[26] Inventoried as State Highway 70L[25]
I-70 BS 0.348[27] 0.560 I-70/US 36/US 40/US 287 in Strasburg SH 36 in Strasburg — — Unsigned. Inventoried as State Highway 70M[27]
I-70 BS 0.396[28] 0.637 SH 40 in Deer Trail I-70/US 40/US 287 in Deer Trail — — Unsigned. Inventoried as State Highway 70N[28]
I-70 BS 0.353[29] 0.568 County Road 153/Main Street in Agate I-70/US 40/US 287 in Agate — — Unsigned. Inventoried as State Highway 70O[29]
I-70 BL 2.80 4.51 I-70/US 24/US 40/US 287 in Limon I-70/US 24/US 40/US 287 in Limon — — Runs concurrent with US 40 and US 287 in its entire length
I-70 BS 0.528[30] 0.850 I-70 in Vona US 24 in Vona — — Unsigned. Inventoried as State Highway 70P[30]
I-70 BL 0.377[31] 0.607 I-70/US 385 in Burlington I-70/US 24 in Burlington — — Unsigned along route. Only indicated on I-70. Entirely concurrent with US 385. Inventoried as State Highway 70Q[31]
I-76 BS 0.472[32] 0.760 County Road 398 in Keenesburg Road 18 in Keenesburg — — Unsigned. Inventoried as State Highway 76B[32]
I-76 BL 52.31 84.18 I-76/US 34 in Fort Morgan I-76/US 6 in Sterling — — Longest business route in the Interstate Highway System. Serves Fort Morgan, Brush, Hillrose, Merino, and Atwood
  •       Former

See also

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References

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  1. ^ a b c d e f g "Fun Facts". Colorado Department of Transportation. Retrieved May 3, 2021.
  2. ^ Colorado Department of Transportation (n.d.). "Segment Descriptions for Highway 070: From RefPoint 0 To RefPoint 500". Colorado Department of Transportation. Archived from the original on May 26, 2012. Retrieved May 2, 2021.
  3. ^ "CDOT & Transportation Facts". www.codot.gov. Retrieved June 11, 2021.
  4. ^ McNichol, Dan (2006). The Roads That Built America: The Incredible Story of the U.S. Interstate System. New York: Sterling. pp. 57, 121. ISBN 978-1-4027-3468-7.
  5. ^ Weingroff, Richard (December 29, 2008). "Why Does I-70 End in Cove Fort, Utah?". Ask the Rambler. Federal Highway Administration. Retrieved June 7, 2009.
  6. ^ a b c "Interstate 25". Dot.state.co.us. Retrieved June 11, 2021.
  7. ^ a b c d Colorado Department of Transportation. "The History of I-76 in Colorado". Colorado Department of Transportation. Archived from the original on March 29, 2008. Retrieved June 11, 2021.
  8. ^ a b c "Interstate 76". 50th Anniversary of the National System of Interstate and Defense Highways. Colorado Department of Transportation. Retrieved June 11, 2021.
  9. ^ a b "Interstate 270". 50th Anniversary of the National System of Interstate and Defense Highways. Colorado Department of Transportation. Retrieved January 23, 2011.
  10. ^ a b c d Staff. "Interstate 225". Colorado Department of Transportation. Archived from the original on July 16, 2011. Retrieved June 11, 2021.
  11. ^ Highway Data Archived July 14, 2011, at the Wayback Machine
  12. ^ Colorado Department of Transportation (n.d.). "Segment Descriptions for Highway 070: From RefPoint 0 To RefPoint 500". Colorado Department of Transportation. Archived from the original on May 26, 2012. Retrieved June 11, 2021.
  13. ^ a b "Dwight D. Eisenhower Highway". Federal Highway Administration (FHWA). Retrieved June 11, 2021.
  14. ^ "Segment Descriptions for I-270". Colorado Department of Transportation. Retrieved June 11, 2021.
  15. ^ a b c Johnson, A. E. (February 26, 1959). "Correspondence with Mr. Mark U. Watrous". American Association of State Highway Officials. Retrieved April 2, 2022 – via AASHTO Route Numbering Archive.
  16. ^ "Why Doesn't Denver Have a Completed Metropolitan Beltway?". stopjeffersonparkway.com. Retrieved June 11, 2021.
  17. ^ "Business Route 25". Retrieved May 2, 2021.
  18. ^ a b Staff, Online Transportation Information System. "Highway 025B between 0 and 1.948". Colorado Department of Transportation. Archived from the original on 2012-09-10. Retrieved June 11, 2021.
  19. ^ a b Staff, Online Transportation Information System. "Highway 025C between 0 and 4.039". Colorado Department of Transportation. Archived from the original on 2012-09-10. Retrieved June 11, 2021.
  20. ^ a b "Highway 070B between 0 and 13.265". Colorado Department of Transportation. Retrieved January 15, 2023.
  21. ^ a b "Highway 070E between 0 and 0.222". Colorado Department of Transportation. Retrieved January 15, 2023.
  22. ^ a b "Highway 070F between 0 and 0.346". Colorado Department of Transportation. Retrieved January 15, 2023.
  23. ^ a b "Highway 070G between 0 and 0.577". Colorado Department of Transportation. Retrieved January 15, 2023.
  24. ^ a b "Highway 070R between 2.188 and 2.711". Colorado Department of Transportation. Retrieved January 15, 2023.
  25. ^ a b "Highway 070L between 0 and 0.400". Colorado Department of Transportation. Retrieved January 15, 2023.
  26. ^ "Did CDOT screw up some highway signs in Watkins and Golden?". Denver7 News. Retrieved January 15, 2023.
  27. ^ a b "Highway 070M between 0 and 0.348". Colorado Department of Transportation. Retrieved January 15, 2023.
  28. ^ a b "Highway 070N between 0 and 0.396". Colorado Department of Transportation. Retrieved January 15, 2023.
  29. ^ a b "Highway 070O between 0 and 0.353". Colorado Department of Transportation. Retrieved January 15, 2023.
  30. ^ a b "Highway 070P between 0 and 0.528". Colorado Department of Transportation. Retrieved January 15, 2023.,
  31. ^ a b "Highway 070Q between 0.137 and 0.377". Colorado Department of Transportation. Retrieved January 15, 2023.
  32. ^ a b "Highway 076B between 0 and 0.472". CDOT Online Transportation Information System. Retrieved March 30, 2021.
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